There can be many sources of the notion that canonical vocations are about pride or a lack of humility. Consider, however, that if God calls some to be diocesan hermits under c 603, it is also the case that acceptance of such a vocation might well be a wonderfully humbling experience. Surely it could be argued that God would intend any vocation to be a humbling (or humble-making) experience rooted in God's love for that person and those to whom they are called to minister in this specific way. No? My own sense is that we tend to associate pride or arrogance with canonical standing because we often neglect to ask ourselves whether or not God calls anyone at all in this way. If a way of life represents a form of divine call, why should we assume that those who seek this specific form of life lack humility or that the way of life lacks sufficient "smallness" where another form of the vocation (non-canonical eremitical life, for instance) does not?
I participated in a couple of conversations this last couple of weeks on a list on "Hermit Vocations" --- a list apparently made up largely (but not exclusively) of self-designated hermits in the lay state. I was saddened to find the degree of judgment I did which is present regarding diocesan (c 603) hermits and the arrogance or pride they were thought to reveal simply in having sought (and been granted!) canonical standing. One opinion was that for those seeking standing in law under c 603 "was all about show" and concern with externals. It is seriously harmful to any form of eremitical life to paint them with such a cynically broad brush and I was surprised to find this response to be so immediate and, in some ways, pervasive. But, to be misunderstood is nothing new with eremitical vocations and I think the question of God's call is critical here: If canonical standing is something God wills for at least some hermits, then how can we automatically conclude that canonical standing and all it brings is something only the arrogant or prideful embrace? (By the way, please note that when folks criticize canonical hermits they tend only to criticize solitary canonical (or diocesan) hermits, not those living eremitical life in canonical communities. I wonder why that is?)
I am not certain what you are asking when you speak of advantages in making decisions in terms of "smallness", for instance, but I believe one's personal discernment can certainly benefit from being concerned with one's own personal and spiritual strengths and weaknesses and how the grace of God is working in the Church and ones own life to make the very best of these. If this means realizing that one sees diocesan eremitical life as lacking in "smallness" or "hiddenness", then it can certainly be of benefit to work through all of this with one's spiritual director. Similarly, if one is looking for a "higher" form of eremitical life, perhaps one needs to spend some time working through this aim and all that motivates it. At the same time, if one is unable to see the real value in lay (non-canonical) eremitical life, the dignity and worth of such life, then one needs to work through whatever it is that causes one to see this form of eremitical life in this way. Whenever we get into competitive ways of seeing that accent "better", "superior" or "lower", "meaner", etc, it is time to take real care regarding what is going on in our own hearts.
That said, it is important to also ask if there are ways each form of eremitical life challenges the other to greater authenticity. For instance, canonical standing calls hermits to understand that the eremitical vocation belongs to God and the Church, not to the individual. It calls hermits to find ways to embrace, live, and express the truth that eremitical life serves others from within the Church --- whether or not the vocation is technically an "ecclesial" vocation or not. Canonical standing emphasizes the place of mutual discernment and formation, both initial and ongoing, and the necessity for regular spiritual direction and participation in the sacramental life of the church. It does not allow one to substitute license for genuine freedom. It stresses the need for a Rule, a vision of how one is to live the life and a commitment which binds in conscience and as well as in law, and which affirms what is foundational and what is not. Lay (non-canonical) eremitical life reminds hermits of the roots of eremitical vocations in the life of the Church, the profound prophetic character of hermit vocations as typified by the Desert Abbas and Ammas --- and others throughout the history of the Western church. These two forms of solitary eremitical existence should be in conversation with one another, NOT in competition.
There are temptations associated with each form of eremitical life. For instance, it is true that canonical standing can lead to the temptation to consider canonical hermits as "better" hermits than non-canonical hermits. This particular temptation needs to be assiduously eschewed and that may require one learning to see oneself merely as called to one valid form of eremitical life rather than another equally valid form. If one has a problem with pride, for example, then perhaps that is a good reason for one's diocese to require one to live as a hermit without the benefit of canonical standing until one appreciates the way God works in and through lay or non-canonical hermits. Even so, the conversations I have recently had remind me that non-canonical hermits can easily fall into the same trap -- that is, they can easily believe they are "better" hermits than canonical hermits because, for instance, they are more like the Desert Abbas and Ammas who did not have (and of course could not have had!!) canonical standing (institutional standing and support in law), or are (supposedly) "smaller," or "more humble," or more "hidden."
But to get back to your questions and what I began this post with, namely, an understanding of humility, in all of this we need to recognize that real humility does not engage in such a competitive way of characterization and discourse. Real humility recognizes that both canonical and non-canonical eremitical life can be rooted in the call of God; though they differ in their relative canonical rights and obligations, both have all the dignity and importance of true vocations of God and both can reveal the tremendous diversity and freedom of eremitical life. It seems to me that one could discern a vocation to hiddenness and to public vows/canonical standing. One has to be certain of one's own motives and discernment but there is no reason to necessarily conclude God cannot call one to smallness, hiddenness, AND to canonical standing. He has and continues to do so.