Also, do they have a "more users, fewer minutes" option? I know I'd rather have 15 users for one minute each, or seven for two minutes each. After that, most users will have decided to stay or flee any ways. It would be good to get a sense of that early decision-making, especially across a statistically-reliable sample.
Cool. They could just give their testers instructions to use the cursor as a pointer to where they're looking. Or you could put that in your instructions to them. It's a decent enough proxy for eye movements any ways.
Have you seen footage from an eye tracking session? A user can't explain or point his mouse to where he is looking. The eyes move quickly and somewhat unconsciously.
Also, do they have a "more users, fewer minutes" option? I know I'd rather have 15 users for one minute each, or seven for two minutes each. After that, most users will have decided to stay or flee any ways. It would be good to get a sense of that early decision-making, especially across a statistically-reliable sample.