Has anyone tried these? How do they compare to the 909s? Do they make the same type of sound? I would love to own a 909 wheelset, but right now, I don't have the money.

Anyone?

I'm kind of in the same situation... I've looked for quite some time at the Renn 575. With a price of just $400 compared to $1000 more for the Zipp, I really can't justify getting anything but the Renn. I've heard nothing but the best about the disc and company. Trying out by friends Renn, yes, they definately does make a very distinct "swooshing" sound, but I don't know it it is the same as Zipps (although I would think it is very similar)

zipp discs also make the swooshing sound

you might want to consider a high profile wheel also, a deep wheel like the zipp 404's or the campagnolo Eurus are good if you plan on doing ANY climbing.