I have a few thoughts:
1. Perhaps it's not the bearings? I noticed on the 3 sets of wheels I purchased on Iplay, that the free coaster (I think that's what it's called?) seemed to have a fair amount of drag. I noticed that when I spun the wheel like hell and held it by the axles, when I used my thumb to stop the cassette, the wheel seemed to lose speed pretty quickly. It seems like the mechanism is sticky or not very efficient. This was with the 772 Novatec hub on these wheels:
http://www.xmiplay.com/ProductDetails1679Like I said, I ordered three sets and they all did the same thing to some degree. Thankfully my set, out of the three, seemed to have the least drag.
Perhaps the Hope hub has a more polished/revised design for the pawls mechanism.
But this shouldn't matter because WHY ARE YOU COASTING?! Keep pushing pedals and don't be lazy!
2. The Novatec hubs that I have are very well sealed compared to many I've seen. They have double O-rings in the hub to keep water out. These O-rings will create some amount of drag. My squeaked a bit so I lubed them slightly. Maybe that helps to reduce drag as well. Perhaps the Hope hubs are not sealed as well or have a better design with less drag.
3. What is the weight of the wheels your brother has? A heavier rim will hold speed better as it has more momentum. Aero aside, a fat guy rolls down the hill faster than a skinny dude. A lighter rim will slow down quicker in my experience. But they are also easer to accelerate which helps with sprints and climbing. Think of the wheel like a flywheel on an engine.
4. Are your brakes rubbing at all? Sometimes they rub without really being audible.
