I don't think that the XT weapons have less recoil.
Instead the "Increased Stability" might imply to the performance issues posed by the guns (Like the M762 causing a lag while shooting or the bug where the Scar-L would shoot up randomly in the air while scoping in).
Just a Theory though, as I noticed almost no difference while shooting with the normal and the XT version of the weapons (Both in Arena and in Classic Livik)
As again, It's just a theory