Ok, help clear things up a bit. .

Also, Boyds offers a Bull channel cut at least (maybe Varmint as well) for their stocks.

I got one on the Heavy Varmint Thumbhole. I am not sure if its mislabeled or I would have to open up, its got the Savage Heavy Varmint in it now and just clears.

I have done the Boyd's Light and an EABCO non bull (you can get a bull cut there as well) as I wanted the stock, didn't want to spend the money and did not want to wait two more weeks for their bull cut.

Its quite easy to do. I just used a dowel and heavy sandpaper, others motorize the operate.

I would go with the largest profile you think you want and then you don't have to do it yourself, all it does is have a bit extra clearance.

I do have the Boyd's light Thumbhole and it can be opened up to a BULL (I did it so that means its true of course

If you go with the Varmint Thumbhole, or Pro Varmint, There is enough wood around the barrel channel that you can open up to accommodate the varmint/bull profile... I don't think the Featherweight Thumbhole has enough around the barrel channel to go much bigger than a heavy sporter or light varmint however.