I've been a user of treadies for quite some time (used them for much of my FLM training in 2000 and this year), but I still find them pretty unsettling for a variety of reasons - see my moan on Wednesday Plodding thread. But for all that, will continue to use them, with all the above provisos (incline, speedwork mostly etc), as and when!
Oh, and Domm, welcome to the madworld that is the Forum!