It is a good thing to have....as a backup.
It allows you to carry less olinemen on the roster. But if you want grade A performance from your line you are usually better served by guys that specialize IMO .... RT/RG is okay, but its hard for most guys to switch sides and be equally effective... so RT/LG is less likely for a guy to be good at both...
Johnson played RG and LT but most reports say he was much better at RG... so RT is probably a better option for him than LT.
I dunno... i played RT on offense, tried LT and couldnt kick slide for **** on the left. Kept crossing my feet... but it was natural and smooth on the right... muscle memory makes a difference.
I believe he is a starter somewhere on this line but if our OC gets injured he could slide over there. I think that's a great option to have. You may have had trouble switching from R to L but there are many examples of some who didn't miss a beat when switching sides. Mauch is one of those guys IMO.