At the very least, the Inquisitor will be able to see Cole just fine. I'm sure of that much. He was in the Fade and got changed by the experience, so it shouldn't come as a shock. Oh, and this probably has been said already, but something interesting was said in The Masked Empire that relates to Cole nicely:
Sure, but, as cogsandcurls pointed out, that ability must be curtailed somehow, or this runs the risk of happening:
Inquisitor: "Man, that Gaspard is a bonafide pain in the arse. Cole, go do that fade ninja **** and assassinate him, s'il vous plaît."
Cole: "No. Rhys said murdering people is wrong."
Inquisitor (looking at some odd 258 bodies lying on the floor): "Err... Buddy, I think at least 49 of those are yours, and that was only in the last 10 minutes..."
Cole: "... ok."
*Achievement unlocked: That Fade Ninja *****
-Skipped 20 hours of gameplay by murdering a major plot character!
Which gamers may be accustomed to, but it grows more jarring as time goes on, and is a great immersion breaker.
(really nice avatar, by the way) 