There are indeed pros and cons to both. But honestly, I wouldn't hold out for in IRS sedan. Having driven a live axle sedan to go and test drive an IRS sedan, and the getting back into my live axle sedan, I can honestly assure you that the difference is not noticeable.
I'm definately willing to agree with you that the Borgwarner diff is inherently rubbish though - I've lost count of the number of centres I've disintegrated with near standard engines.
_________________
green200b - aka Alistair
The fleet:
Australia:
'80 200B GX - the
green200b - hibernating
'81 RX-7 - 12A extend port - daily
'74 RX-2 - 13B bridgeport - cruiser
Europe:
'93 200SX - CA18DET - tourer
Green200B has forgotten more about 200Bs than we will ever know.