I currently have the 60028s...they're not too bad. The stock ones were shot so that's all I have to go against. Thet're stiff, but not jarring. I've noticedd its a lot better going over all the bumps back and forth to work in the last week.
That said, I think you'd be happier with the Billies. If I had a chance to get them, I would. I just got a great package deal on the OMEs. You could even go a little cheaper and get Bilstein HDs...I've seen a few guys use them with 906s, and they're probably a little cheaper.