The only thing I'd be cautious about is the size.
If you're brewing 5 gallons on a fryer setup in a 10 gallon pot, it's just a matter of time before you'll want to do 10 gallons.
The step up to a 15 gallon pot is relatively small.
Just Sayin.
Bull
I don't think it's a given that everyone that is currently doing 5 gallon batches will eventually want to do 10. Most of the homebrew supply houses seem to be geared for 5 gallon brews, and much more than 5 gallons would get too heavy to move around. I don't see myself ever wanting to brew more than 5 gallons at a time.
Now it you said that some 5 gallons batches would require a pot bigger than 10 gallons than would be a factor.