I think the Jaguar system was cobbled together after they were bullied into using the Ford parts bin to avoid the shame of making a front wheel drive car - not that they avoided that for long.
It goes without saying that a 2wd transmission has a handy torque limiting device namely the traction available from 2 driven wheels. Double that and you have to think about the torque rating of the whole transmission again. Bolting a bodge onto a FWD gearbox might have kept the beancounters happy but I suspect this car has become a victim of that decision.
XJR looks much more interesting. I was given a rather rapid lift across Munich in one of these a few years ago and couldn't believe it was "just" a V8. It had all the refinement of a V12 jag and was seriously quick. It'd still be a brave man who took that on, though.
At least the "known issues" with the Omega, Rover K series, etc are rarely terminal and replacements are easily sourced if it comes to that.
Kevin