If I had the extra cash, I'd like to take a Howa action, put on the heaviest match 30/06 target barrel, trigger, heavy bench stock, and a good recoil absorption system and start using all the '06 brass I've got sitting around. It would be used for long range shooting.
The tube gun sounds great but looks terrible.
I think it would hold it's own with most other calibers. Might take a 210 grain bullet to do it. Just dreaming, but maybe someday.