I have a M15 myself, very good deck, much better than the DSR-11 it replaced.
Where I work we have the M25, same transport as the M15, adds HDMI output and will play 720p taoes out component only. Also it seems to be the only deck that'll "clone" a HDV tape. Big attraction of the M25 is it has an LCD screen, can be very handy in some applications.
There's also a WAY more expensive HDV deck, 1500 or some such number with option modules and HD SDI ouput.
My biggest gripe, nothing, not anything, will encode HDV from HDMI, component or HD SDI. I think Miranda have a box that'll do it for some staggering price.