Wait wait, £200??? That's WAY less than I would have imagined based on the parts list I saw on the post I linked to in my original post. One of the posters there did a rough cost estimate and came to around $2400 all in (new parts though).
But for that money I'd do it (or have it done!) in a heartbeat, especially as it sounds like it would improve handling over the original handling anyways, although to be honest I never really had any complaints about handling with the few Z4s I've had.
You lucky SOBs in the UK seem to have access to a very very affordable second hand parts collection, something I haven't encountered in NL. Everyone here just wants to make as much as possible off of these parts, even the indies. I'm jealous