I run a XXX-SCT with the TLR tuning pack and TLR 22T shocks and it's an awesome truck, very competitive and very strong.
Upgrading to XXX-SCB chassis when it arrives to help get the air out from under body when jumping.
The only gripe about the XXX SCT/SCB platorm is the wheel fitments, it means you have to use odd sets front and rear plus the bearings in front give a lot of play after a few runs... i've fixed it though... Proline do an inboard bearing 12mm Hex conversion which uses same geometry and means i can run same 0 offset wheels all round.
Great Platform and the XXX-SCB is a really nice looking scale buggy, so would go for one if i wasn't racing the truck already, A1 Hobbies have more in stock, which is where i have had a good look over them
As for a 22 SCT version, Losi do have a version in testing but it'll be a long time before any announcements... RCRD have a chassis about to launch in USA which converts the 22T into a SCT with some customising needed to it bumpers and body mounts, would be an improvement on XXX-SCT with being able to run mid motor, plus parts are easier to get and it would handle bigger power, i'm a big fan of 22 platform but can't warrant cannibalising my 22T when its too shiny and new atm!