Before I purchased my 2009 Z, I send it to a BMW dealer for inspection. I asked, among other info, about the top and its motors. They stated that there have been no "Regular/repeatable" top issues to date. The dealer also stated that the long term jury is still out on the robust nature of this system.
Wtih the E89 having so many major complex systems, component longevity untested and absolute guaranteed high repair cost, the extended warranty was my personal solution. I looked at the cost of the DCT-$14K, 4 motors for the top- Probably $500 each, Twin turbos-$1K, cooling system $$$???, electronic suspension $$$???, electronic parking brake system and on and on.
The $2,640/3 year NMW GOLD insurance policy will be well worth the price of admission for peace of mind even if there are no claims.
2009 BMW Z4 35i/SMG/DCT/Premium,Cold, Sound PK/Com Acc/Ash/PDC/Wind Deflector/Smoked Reflectors/Red Calipers/Cl Mask/M Series Grill/6000K LED's/De-Badged/M Pedals/CF Mirrors/Stubby/20% Tint/H8 LED's/LCI Side Markers/Super Sprint Spoiler/VMR V710