Ditto here! A DD is not going to suffice for turbine sign-off as far as I am concerned. It does not prove to me your capable of handling a heavily wing loaded, multi channel aircraft. No gear, how do I know you can even land?
David is right on here, there are plenty of used DF aircraft on the market that can be bought for 800.00 or less and presuming you don't destroy the airplane in the waiver process you can certainly get your investment back when you have completed you sign-off (if you do destroy it, maybe your not quite ready for turbine?). I am more concerned with you being able to handle an airplane with flaps and retracts than the speed. Although speed can get you into trouble fast I have seen more guys have trouble with landings (including myself) than anything else, how can you prove you can land a plane on the centerline and keep it there with a DD? Can you get the plane into slow-flight and hold your approach?
Nope, DD wont cut it....Sorry!
Todd