I had friends shooting a wildcat version of the 6.5 and 7mm x .300wby as far back as the late eighties.
There are quite a few 6.5mm STW's around as well.
Is it too fast? Well not if you have a bullet that will stay together and shoot accurately.
Are you going to burn out a lot of barrels? Well yah, you will if you do much shooting with any of the seriously overbore 6.5's but nobody is going to build one with barrel life being a consideration any more than someone would build a dragster or funny car thinking of the day they'd turn 100,000 miles on the odometer or do so with the idea of having a practical high mileage "Sunday Driver".
The 6.5CM is a Toyota Corolla to the 6.5mm dragsters.
Personally I think the .264wm is where you hit the wall of practicality/velocity. Pushing them any faster comes at a great cost in powder and shortened barrel life but for those who enjoy the ride I say, "Go for it".