I recently moved my tortoise outside full time and I got to thinking, are outdoor Torts more prone to illness than indoor Torts, Being that they're outside and exposed to the elements vs indoors in a controlled environment?
Too many variables in either scenario! They will be healthiest being kept in the correct, safest conditions either indoors or outdoors.
Mine is outdoors, of course, being that I live in the tropics! Absolutely no health problems so far, probably because I make sure to bring them inside in their indoor enclosure when it gets too damp and cool outside for them.
You can expect a slow down of the growth rate for at least a few months when moving them outside full time. It doesn't happen that way for everyone, but it seems to always happen that way for me. Keeping up with soaks seems to help too.