I was thinking more of a "proper" intercity train with single doors at the end of each coach as well as the appropriate seating rather than a regional train modified for intercity purposes. "Proper" probably wasn't the correct word for it, but I was definitely meaning a train more along the lines of a Class 390, 397 or 80x train, or more appropriately the SBB Rabe501 Giruno sets
The Girunos don't have single doors at the end of each coach. They have them somewhere in the middle as per all FLIRTs - the reason FLIRTs have doors in the middle is so they can have level boarding, you can't do that over the bogies, and there's no "throw" past the bogie unlike on non-articulated stock. OK, it's a single leaf, but if you're only going to have one doorway per side per vehicle it's better as a wider one with two leaves, the SBB tendency to use wide single leaf doors mean operation is very slow.
While the Giruno is a faster (140mph I think) train than the FLIRT, I don't think a suitably configured FLIRT is any less InterCity in ambiance. The boundary between "regular speed IC" and "regional" is rather blurred these days, with 100-110mph pretty much the standard top speed in that market.
I don't think I've ever ridden in a nicer InterCity train than the PKP high-floor FLIRTs, by the way. Lovely things, though not great for access; they really could do with one low-floor coach for the wheelchair spaces. And while I do quite like the 397 and 80x, I'd take a GA IC FLIRT any day, it's just a better quality product with a far better ride, plus the game-changer of level boarding. And I'm not sure how the very comfortable FISA LEAN isn't an InterCity seat, it's far better than the Sophia as in 397s and 80x.