Yes, i have over 13,000 traditional Ohio caches from the beginning of caching in the state, all loaded as custom POIs which end up on the SD card

We use 4Gb as a minimum and have no trouble with those and larger cards. The point is that with the maps, its not the size, but the number of map sectors you can save. So we have the entire continental US street level routable maps loaded on to the card along with the Ohio Topo and have some room to spare.