Barnzy7, it basically boils down to what you want to do with the car, and what you expect the car to do for you.
Honda's are incredibly dependable cars, and thanks to there abundance, it dosen't cost nearly as much to mod them to what ever level that you desire.
In "Bone stock" condition, about the only thing an SRT will do better than the Honda is out accellerate it in the 1/4 mile, by about a 1/2 a second. Of course it will probably keep that same lead to its (restricted) top speed of 155 mph. (156 mph for the Honda).
The cars go thru a slalom course at nearly identical speeds. Crossfire 69.6 vs 69.7 for the S2K.
On a road course the S2K's rack and pinion steering will feel light and tossable, compared to the more heavy "feel" of the Crossfire's recirculating ball arrangment. In the end, it would probably boil down to a drivers race. But IMO, the XF's H.P. would probably still come out ahead.
Styling is purely subjective . But everybody here will tell you, the Crossfire turns far more heads, with out a doubt. I would think that the Crossfire (essentially being a Mercedes) would also have a more expensive "feel" as well, when compared to the Honda.
I wouldn't be afraid of a S2K with 88k miles as long as it hasn't been too abused. The same holds true with any Crossfire. Have both cars checked out by a reputable tech. before spending any $$.
Good Luck.