I went with the GM hitch. More than happy with it. It meets all of the tow ratings for the SRX. Just because you put on a larger hitch doesn't mean that you can carry a heavier load.
The Gm hitch was a snap to install and comes with all required hardware, wiring, bolts, etc.
It also nestles nicely under the bumper when the hitch is removed from the receiver, I don't care for the look of all of that extra iron sticking out when not in use.
I think it is a very nice looking installation.
Got it from GM Accessories Store.
(Same hitch for 2004-2008)
http://gmaccessoriesstore.com/cadill...c-388_549.html
$286.38 + shipping.
Took about 45 minutes to install the hitch and maybe 5 minutes for the wiring.