> But a sighted user will be much less proficient at using anything like that
Not only that, but they'll be stumbling around not really knowing how vision-impaired users actually work with their devices, so they would have issue an impaired user would not have, and not hit issues an impaired power-user would.
But a sighted user will be much less proficient at using anything like that, so it is probably better to find someone who isn't sighted and so does everything like that. Otherwise it will take far longer to recognise any issues