It depends on the situation. If I'm playing for dancers, I stay on the 1 religiously, unless I know the dance well, and I'm sure it's a spot where the footwork isn't as critical. In a session, I'll throw in the backbeat as a variation once in a while. There are a couple of players here that like to get a little funky here and if I'm playing with them I'll bounce around a bit more. If it adds lift, throw it in. If it just clouds the rhythm, don't. As a player of the instrument that's simplest to get started with, we have a responsibility to the others around us. The most important part of any accompaniast is his ears. Listen and lock in on the strongest melody player in the group. The backbeat is a variation and as such should be the exception. I'd recommend you listen to some recordings of good players, particularly Johnny McDonagh. (Arcady, DeDannann, Mary Bergin's solo CDs and others) Finally, remember the backbeat is a specific point in the measure. Don't just accent randomly.

Good luck,
Rich