I work for a BMW dealership.. I like the PE but its certainly not "refined" sounding... it's the most raspy/higher pitched out of all the ones mentioned. Sounds cool, but not as refined sounding as the Vanguard.
That being said, I have a Vanguard. It has a super deep smooth bass-y sound with stock downpipe, in fact I thought it was rather quiet.
With a catless donpipe it's PURE SEX. Gurgles and pops (but in a bass-y way, not tinny sounding like the PE), backfires on WOT shifts (especially with E85 in the tank), and generally sounds super exotic.
However... fully catless, it does drone a bit between 1700-2000 rpm in 6th gear. I've changed the way I drive to avoid this. Basically I stay in 4th gear at speeds below 45mph, and 5th gear in speeds up to 60mph. I use 6th for highway speeds and that keeps the RPM over 2k and no drone. I've lost about 0.5-1.0mpg (if that's even a measurable amount - it's cold out), but I'd *NEVER* give up the sound because of it.
As for install... if you have a lift and some patience, it's not a big deal. I spent about 1-1.5 hours aligning the tips by bending the muffler hangers and messing with the cross brace between the mufflers and finally by placing the adustable tips. At least there are adjustments to be made - you can make it absolutely perfect if you want. Some setups you have to live with "pretty close."