How does it shoot now without any bedding?
Doesn't McMillan state that you shouldn't need to bed if your stock is made for your specific rifle?
If it is shooting to your expectations now, I would say do not bed.sub
Theoretically, a full length bedding is supposed to be 'better' vs only bedding the recoil lug area, but that is probably 'rifle specific'. I had a rifle that I bedded only the front area of the receiver, recoil lug area, and the first 1-2" of the barrel. This rifle shot sub .5moa.