I posted on the Hydor thread, but a search of Nanostream on
Nano-Reef.com - The source for nano reef aquarium information will bring up a number of problems with Tunze's clip mount for those pumps. I haven't used them, though, so I can't say it's accurate.
I can say I love the Hydors I have (Model 3 and 1). Especially over my old Seio 620's which had startup problems after feeding cycle. My Hydors always start and I've never had them reverse on me. The open cage design is a bit bigger than the Tunze's, but it essentially puts the whole flow on display. Plus, the helix-shaped blades don't chop up things that do get sucked in so it's not an in-tank Cuisinart. I also like the ball-joint magnet mount. Very easy to position and infinitely adjustable.
Now that they've fixed the voltage leaks and given the price difference, if you're in the 1200
gph or less market, I'd say Hydors are your best bet.
