Well, you and your brother are asking the wrong crowd!!!
Go to http://yamahajetboaters.com/
and post your questions and see what Yamaha owners think?
If your brother is a hardcore boarder/surfer/etc. I'd be the first to tell him that it it is definitely not his cup of tea. You can add ballast, etc. for a bit more wake but the jet wash area is definitely something a good wakeboarder would not like.
If he is a recretional boater that likes to enjoy spending time with the kids and family like 90% of us and don't want to worry about maintenance or repairs or replacement of props, the Yamaha is definitely something he should consider.
dcooper - The low speed issue can be tame with the addition of Cobra Jet Steering. Mention it to your friend so he could look into it. It's relatively inexpensive and very effective at low speed and even better in reverse.