The C32 would blow the doors off the R in the wrong gear, and mildly modified, they can beat car like F360s. I like the feel of the R driving through twisties at 6.5-7/10th better, but once you start pushing it a little more, the C32 with RWD shines. They have about the same amount of room. A quick check of the interior dimension on a site like edmunds.com will tell you the same thing. The R's seat is more comfortable. The interior looks better in the C32.
Given the prices on C32s, I'd opt for one. A good friend of mine owns one, and he gets better gas mileage than I did in my R by a significant margin. The Supercharger is engaged by an elctromagnetic clutch, so it stays idle until boost is desired. Overall the interior is better in the C32, I think. Seat comfort in the front is still better in the R. The only time it feels smaller compared to the S60R is carrying 3 people in the back, and the R is already very cramped and uncomfortable with 3 people in the back, so you wouldn't really loose much there. It's in a different league than the R performance wise, and unless your R is trapping at 109+, you aren't keeping up with one. Without a speed limiter they top out just over 300kmh (186mph). I think they only one on this forum who could outrun one (in their Volvo) is Johann. And they can get to the power levels he's at without radical modifications.
Even with snow tires, the C32 is a little exciting in the snow... Despite a good weight distribution, it still gets VERY tail happy in the white stuff. The plethora of electronic nannies help with that, but it's still something you'll notice. The R is WORLDS better in the snow than the C32.
If you must have a manual, than obviously the C32 isn't for you. That said, the automatic is very good as automatics go. The Manumatic mode is much better than that on any other car I've ever driven. Even so, I'd say that the slushbox is that car's downfall, just as the FWD biased AWD in the R is it's downfall. Whichever way you go, you'll only get half of a performance drivetrain. It's your call whether the RWD or the Manual is more important.