The foam grips look a lot wider than the lock ons. I thought they might cause arm pump?
They might be, not sure, they don’t feel big anyway, the ritchey ones are either ergonomic or normal shaped (ones symmetrical and the other bulges at one side of the centre to fit your palm) and the narrow bit are quite thin, and they’re squishy so you don’t notice if they are thick. Guess what that tried to say was “I don’t notice them while riding so they must be doing their job really well”.
As for riding in the wet, superglue them to the bars, just a little drop at each end, once they wear you can just cut the grip off and acetone will dissolve the glue.
[edit] I tried some cheep foam grips before the ritcheys and wrote off foam grips as being useless with no feel for the trail (I kept crashing after the front wheel would wash out). Whether the ritcheys are better of if I was just looking for a component to blame I’m not sure, but I’ve not had any problems since then.