Z3M Roadster - opinions?

So, I've been having a bit of a peruse on AutoTrader, and these seem very keenly priced. They're a good deal cheaper to insure than I was expecting too, which has set me thinking!

Anyhow, is there anything I should know about these cars? Weak spots? Common issues? Servicing and running costs - are they insanely expensive to keep going? Cost of replacement tyres, pads, etc?

Any and all thoughts welcomed - particularly regarding the direction you see their prices heading over the next year or so. As the Z4 continues to hit the used car forecourts, will the Z3M prices collapse?

I'm very close to looking at one for sale near my parents over the Xmas period, and I may get carried away...

Cheers,

Dan

Interesting stuff so far! Not sure I like the sound of engines grenading, but still - I assume it's rare? Choice at the moment seems to be S2000, Z3M or Audi TT - possibly Boxster if I really push the boat out.

TT's very insurable (only +100), S2k's expensive, Z3M's middle ground. Boxster expensive. Hoping for a test drive in the next week or so - should make my mind up!

Dan