This is how i´ve seen it from the get-go : The “X” is a T3 (why mess with the success ??) with a modular stock (doesn´t matter to me since i Always use GRS stocks on all my guns), steel rec lug (which every owner changed to anyway – preferably for Stainless steel which the oem lug is not), a modified load handle (that still isn´t as comfy as many aftermarket handles) , an aluminium bolt shroud (that looks like the plastic one and i´d change it anyway since i don´t like the look of the oem) and a weakened action due the enlargened load port.
The reason i didn´t take my Super Varmint as an “X” is: I can´t see any reason, at all, that makes the X a better buy for me. Quite the opposite.
However : Those who have their Tikka in its OEM stock the “X” is a no brainer though. In Europe they cost the same as the “old” T3 so for those guys it´s a better choice.