Two things have kept me from carrying via ankle holseter -

1. At a few LE trainings and conferences I've seen officers sit and cross their legs or ankles, or adjust the length of their trousers as they sat, and apparently not realize they have just exposed their ankle holster. Didn't seem like a good "concealment" strategy to me.

2. While assisting a partner officer with serving a warrant, the bad guy bolted, my partner tackled him, got twisted around in the brief scuffle, ending up atop the BG's back, facing the BG's feet, with my partners ankle holstered gun much closer to the BG's hands than to my partners hands (which were about three feet away at the BG's small-of-back). I drew my gun and warned the BG not to reach for my partner's gun (not a great angle for me to have to take a shot, but better than allowing him to reach for my partner's gun). This one really made me uncomfortable with ankle carry.