I tried to get together a group buy for a cytech doublepark (like the prowler club did) but didn't get any interest.
I ended up buying one anyway. Everyone does a lot of research and comes up with one of these 4 listed.
I almost purchased the PP7k, but after the corvette collapse, and the fact that they never paid the guy off for what seems like a product fault (or at the very least they strung him along for 4 months), I switched to cytech, which has never had a collapse, and seems to be the only one tested to 21k lbs.
If you're interested in the sad saga of the perfect park collapse, there are some old posts here directing you to the corvette board, or you can goto the corvette board directly, he was very detailed in his anaylsis.
Oh, after his collapse, he ended up getting a cytech, which also swayed my decision.
Don;t get me wrong, any of these are going to work the same way, and probably not cause ANY trouble, BUT if something DOES happen, I want to be taken care of, so that's a big differentiator to me.