It's reasonable to expect everyone is able to use a lowest common denominator. But, it's unreasonable that you stick to the lowest common denominator if you're

It's reasonable to expect everyone is able to use a lowest common denominator. But, it's unreasonable that you stick to the lowest common denominator if you're going to be using your own setup 99% of the time. I'd say a bigger disadvantage to non-traditional setups (trackballs, non-qwerty, small keyboards, etc.) is "others won't be able to use your stuff".