I have used this mod for a very long time. So far, I have not had any problems but until very recently my understanding of how mods can effect the game has been exceedingly limited. Despite this, I felt it would be worth it to add my two cents, considering there is only one post so far and others may come along in the future and wish to know a little more.
Here is what I have noticed:
CTDs: During the entire time I've played Skyrim (almost 600 hours) I have had very very few crashes to desktop and that did not seem to change after installing Dynamic Merchants.
Lag and Freezing: I have not had any significant lag. My game froze once recently and before that, I can't recall if it ever did. There is no reason to believe the freeze had anything to do with Dynamic Merchants.
Save Bloat: I haven't noticed. I don't really understand much about what types of mods can cause that (I'm still learning). If this has been occurring, I haven't seen it. Load time has been, for the most part, the same or at least reasonable. A while back, there were a few times I remember thinking it was taking a long time to load but I believe that was before I had this mod. Now that I am aware of save bloating and some of the problems it can cause, I will keep an eye out for it and update this post if I ever come to the conclusion that this mod causes it. I really really doubt that it does though.
Misc Glitching: I have not experienced any glitches that have recurred, nor have I had any glitches that stood out as possibly being related.
I have noticed the decay rate is a little high for my liking also. It required that I have a couple primary merchants or that I run around to merchants all over the map in order to sell all my loot.
Overall, I love this mod even with the high decay rate. If the way merchants work in the vanilla game just really gets to you (as it did me), this is not a bad mod to use.