I've tried all 3:
1) Jazzy
2) mvigneau
3) Leptronix
1) Jazzy setup - it was a clean and easy install, no soldering. It's just annoying that you have to have a CD running all the time. It worked very well 99% of the time, it's just the Subaru system does not remember if you had Repeat on or off, so next time you start up, you have to remember to switch on the repeat.
2) mvigneau - quite complicated, I'm very comfortable with a soldering iron and had minimal trouble installing it. It was a CD-less install and I liked the "Aux button" modification, but it suffered from power on problems - but it's a standard problem with anything using a relay, a slight toggle of power/mode and it's not sure if it should be on (aux playing) or off (CD/Radio playing)
3) Leptronix - clean and easy install - just one minor bit of soldering that I think it would take minor soldering skills. In installing/un-installing the previous 2, I'm quite adept at removing the unit out of the car. I like how it functions - just start playing your aux device and it eventually switches between aux and CD/Radio. I have not permanently installed the 3way switch, which I may do sometime soon.
In order of preference, I'd recommend: 3, 1, then 2.
All 3 had very good sound quality. Which ever of the 3 you decide to get, definitely read the forums for each - there are some very useful tricks to making the install go much smoother.
Just my $0.02.
