In some cases I would say yes but just realize that you're in the arena with some of the most spohisticated and tech savy firms in the world with much deeper pockets and resources than an individual.
Nothing wrong with speculating in vol. Probably easier ways than dispersion, though. Like you yourself said, a lot of slippage there when you're dealing with so many instruments. I've always wondered about speculating in vol between options on commodity ETFs versus options on the underlying future.