Has anyone tryed using a poly bush instead of the rubber ones on the front diff bush on the mk1 freelander would love some advice as mine is in need of a change and im considering trying one instead of the rubber one. Thanks

nope - yu try it and let us know .

Yeah, got one fitted to the front bush. Easy to fit and has lasted longer than the genuine rubber things. Got it from Flo-Flex Polyurethane on t'web.

Are there more advantages / disadvantages to using polyurethane bushes?

Advantage- Last longer than rubber and are slightly stiffer. I have been replacing worn bushes with the poly type and have noticed a slightly less 'wallowy' ride.
Suspension bushes are basically the same to replace as if using rubber.

Disadvantages- Slightly more expensive, but diff bush has lasted longer than 2 genuine rubber bushes.
You have to retain the ally housing from the duff rubber bush and insert the poly into it. I made a press using a bench vice, big sockets, sticky back plastic etc. etc. but it was easy enough to do.