I personally think after owning both that there is no comparison between the two. If you find an IQR that has been done right to a T (trust me it's hard, many out there are hacked together) it is not even as good as the older IQ Raw chassis for mountain riding IMO.
The pro just has it together, the boards are narrower to promote steeper angle side hilling, the footwells are better, the rear suspension geometry is more conducive to climbing, and it's so much narrower in the body that you don't "panel out" like an IQR does. Thats probably my biggest complaint with the IQR is that it panels out so easy cause the body shape is kind of round and bulbous.
I would hands down no question get a pro or an IQ raw over a modded IQR again.