Actually, according to the data from the training speed analysis, 1v1 for forwards should increase handling and driving faster than 1v1 for guards. Jump shot is a bit slower for 1v1 forwards, but then there is the added benefit of inside shot training, which doesn't happen at all when training guards.
Overall, I think it's much better to use 1v1 forwards whenever you can. The difficulty can be finding weeks to play your guards out of position in SF. Well, that's not too bad, but in those weeks you're gonna need a PG to help the offense, and then often you can end up with a big man in the SG spot. Neither of those lead to lights out offensive production.