I discovered tilapia, and started to like it. Could I use tilapia for recipes that require sole?
Yes, the flavor and texture are a bit different but from a technical perspective it would work.
Fillets of sole are typically a bit thinner and more flexible than tilapia so if it's a recipe where the sole is to be wrapped into a paupiette (rolled package) the tilapia would have to be shaped differently (such as layer the filling on top of the tilapia fillet instead of wrapping it, or sandwich the filling between two smaller pieces of tilapia.)
Besides the fact that you like Tilapia, the other benefit is that it's less expensive than sole.