i agree with what was posted here, too. the extra 2 resources can be pretty huge. i often strongly suggest to folks running m2m/zone who are newer to d1 recruiting to intentionally take walkons, to help get in the mode of battling and dealing with unfilled openings (which will come through the competition and EEs regardless of your intentions).
but for d3, my take is this. more players is going to be better for you, and you mostly want to aim for more players and then use that 10 player allowance as a buffer. its not like you can go around battling like crazy in d3 with that extra money, although i'm sure the resources still help considerably, but you also have more reasons to fill those spots than in d1.
there's a few reasons more depth gives pretty big benefits even in man and zone. the main one is that your 7-10 core players are on average going to be significantly more experienced and more developed, if you are pulling them from a set of 12 players as opposed to 10. also, the same-season benefits are significant if you are playing a bunch of press teams, and especially if fb/fcp teams, which as a d2 or d3 coach is virtually guaranteed. this is more important as you get more and more competitive in the spectrum; going from 10 players of depth to 12 is more valuable when you are going for deep NT runs than going for a NT bids up to S16s.
finally, even with 11-12 scholarship players, you may only have 10 active players if you use redshirts, which i would highly recommend (redshirts are especially great for programs building or rebuilding, and for m2m and zone schemes, so you are hitting both sides of hit), or if you recruit ineligibles in recruiting, which is something you'll likely want to do from time to time (again, ineligibles can be especially beneficial for programs on their way up, and for m2m and zone teams who can much more easily tolerate that non-active year, and you hit both).
in summary - having 10 players is fine - but in your position, i would try for 11-12, and use falling to 9-10 players as a buffer. when you get to d1, you'll have much better reasons to consider taking walkons on purpose.