(Random thoughts from an amateur)
In re: the debate between australopithecus and erectus and sapiens.
Erectus reached Flores about 840 kys. How likely is it that autralopithecus not only got out of Africa but managed to cross a fair bit of nasty ocean to Flores without leaving any pesky fossil evidence along the way?
Does anyone know the fossil history of sapiens on Flores? If there were "normal" sapiens present all of that time, then would there have been enough breeding isolation? Also, by the time of sapiens I would think that we'd gained enough control over our environment to be less susceptable to the type severe, rapid drift that would be required to produce floriensis in such a short time.