Pioneer2
Gotta agree with one of your assumptions... loading a PRB in a QLA is not the best thing in the world... but,
Not all QLA's cause accuracy problems with conicals - some certainly do but not all... You will need to shoot the barrel and find out. My hunting partner has a 54 Hawken with a QLA and his seems to shoot just fine, but other do not.
If you are thinking of buying a new barrel - get a Green Mountain IBS they do not have a QLA.