I had a BTM exhaust fitted a couple of months back now and really do like it, I have no experiance of anything else on the car other than the original Renault system.
It's cat back and on idle it's a smidge louder than what my standard exhaust was like. On motorway and at steady speeds you can barely hear it in the car. You get a decent note when you put your foot down, and it doesn't wake the neighbours when you start it up in the morning, even the girlfriend approves. It's not as raspy and no-where near as loud as the Yozzasport.
You also get a new style rear exhaust hanger so it fits in the bumper cut-outs perfectly and it's something like 8kg lighter than the standard system (so I was told) .
Other thing I have noticed is that power delivery seems a little bit smoother, getting rid of some of the 5k kick.
Had it fitted by Fred at BTM Performance although you could also have it posted for the same price, which was £490.