The prairie hunter on a Rem 700 ADL felt great, a noticeable jump in weight compared to the factory tupperware, but not what I'd say was heavy or misbalanced for the standard weight barrel.
I put a Featherweight Thumbhole on a Savage B-Mag, it's remarkably light. It has a wide, flat forend that's more sculpted than I anticipated, but I like a lot. The heavy barreled B-Mag felt TERRIBLY balanced in the factory stock - too much weight up front and nothing in the back, but the Boyd's featherweight thumbhole balanced it out very cleanly for me. It still feels like a rimfire rifle by weight, but handles more steady like a heavier cf rifle - without the weight.