I'm so glad this bike fails on geo and vfm for me. Less chance of buying things I don't actually need.
Same size rear centre across all sizes?
Deceptive STA measurement to hide slack angles?
Proprietary shock?
All the things I don't look for in a bike. Might work better in smaller sizes. But in XL it's a hard pass.
I can help.
Rear centre is 437mm which is a bit goldilocks depending on what you're after. I think Trek are still stung by the semi-trailer criticisms they got for their old 29er Remedys having 445mm chainstays.
Seat angle of 76 degrees sounds okaay - it looks slacker than it is cus of the kink in the seat tube to allow for rear travel.
Bike can run pretty much any shock according to the Pinkbike article.
XL size is pretty big? Plus mate who's my height (6'5") has been crashing around on the previous gen Slash and reckons it's the best bike he's ever had.
Go get your credit card. I'll wait here.