You are probably right bookworm, 1300m was only a very rough calculation. The more runway the better....
What would your estimation be though of the Comanche's to climb away between 90mph (Vmc) and 105mph (Vyse)?
Piper seem to think that you'd be OK at 97mph (described as the 'take off safety speed' in the POH) but I've yet to meet someone who has had a very low level failure who can 'tell it how it is'.