There are definitely some slugs up here, my pak choi has been eaten a little bit, although a lot less than I find them on ground level crops. Sometimes I sprinkle some egg shell pieces around the crops, it keeps most slugs away except for the stubborn ones. The main problem is summer heat. Containers dry out very quickly in full sun, unlike a piece of land which always keeps some water and nutrients stored in the ground in clay and other absorbing particles (which is why I'm looking for clay loam too). On real land you also have worms naturally making the soil more well draining. I use perlite and hydro clay pebbles.
Up here it's always very hot in the growing season. Even worse than on the ground, so my peach tree may do very well here. Lettuce struggles during summer heat because when the temperatures hit 90°F (it does every summer) the balcony feels more like 105°F because the sun is always on here. Don't want to put my chair there anyways, except for late evenings, maybe...
Perhaps the temperatures are not even that bad as I love tropical fruits so much