Wall mount remodel options - re-use carrier or install Geberit/Walvit?

I am remodeling a 1960s basement bathroom with an existing wall-mount. The location is fine and the carrier is nice and sturdy. It seems there are 2 broad options:

1. Stick with the existing installation and get Terry's recommended AS Glenwall. I do plan to subway tile the wall, and I can bring the backing nuts on the carrier bolts forward the 1/4" or so required, but the threaded flange is currently only 1/2" beyond the existing sheetrock. The heavy cast carrier is labeled "JOSAM" and there are sort of teeth around the circumference behind the wall. Does that mean it is two separate threaded pieces and I can unscrew the flange a little to bring it forward to adjust for added wall thickness? Haven't torn out the drywall yet to see the details behind the wall.

2. Tear everything out and go with a sexy Geberit or Caroma Walvit in-wall tank unit. Relocating the supply to the top of the unit would be easy, but I'm concerned about the existing cast stack tied to the carrier and the possibility of having to cut that down to tie in to the new system. The benefit is the clean installation with no visible tank. The downside the overall huge amount of extra work. But if I can't adjust the existing flange to accomodate new tile on the wall, I might have to tear out the wall anyway?

Another consideration: We will likely add a Toto Washlet, and these only fit more traditional shape round or elongated bowls, so that reduces the appeal of a Duravit. I wish Toto made a wall-mounted Neorest!

Thanks for any suggestions!

go with the American Standard. The mounting spud is screwed into the face plate so it can be removed, new joint compound applied, and then reinserted. Unless it has a gasketed locknut, in which case you can loosen it, readjust the nipple and tighten the lock nut.