The Victorian Police, in which I am a member of, use the SS commodores for one reason. They are a hell of alot quicker than the XR8's. Both have had their quality concerns. We also use the WRX's, but speaking to many a toggie, they prefer the SS's, as they are more roomie(allows for the McGuts to fit in)and over 150kmph the SS's eat the WRX's up. Some have said they prefer the XR8's handling, interior etc, but it lacks the go, or the business end of things.
The 220kw motor, a little more top end, I am not sure exactly on torgue, but really no great performance increase. Still a dated motor that simply lacks the cubes or tech upgrades(ie OHC's).
A couple of years ago we were still running XR8s as they were a hell of alot better than the early VT's.
Speaking of the SS. I was in one the other day with a Toggie, and we were pulling out of a McDonalds car park, and in reverse were getting a horrible crunching sound from the diff. He said it is common.................
p.s Toggie = TMU (Transport Management Unit) "Mad Dogs Chase Cars"