This is my 50 cal GPR with the Lyman sights (peep rear and globe front). I have no problem with that sight being in the way of my thumb or anything else. I purchased a set of inserts from Brownells that I like much better than the ones that come with the Lyman sights. I hunt with this rifle and compete in matches that allow those type of sights.
I did glass bed the tang and barrel and I never remove the barrel from the stock. Ever. It gets cleaned with a flush nipple and plastic tubing, good brushes etc.
I have other rifles with primitive sights for matches that call for them and rendezvous shoots. But this is the rifle I prefer to hunt with. Its reliable and those sights are kind to my old eye sight.
Hope this helps answer your question.