Thanks for the responses, I agree that there are some excellent recorders designed for dslr use, but they tend not to be ideal for general use including handheld use in the field in my view (this has to be personal in the end because I buy for me to use (usually). I already have desktop units and in general my existing video recording audio equipment is adequate for my current needs, though I must admit being tempted by the DR 701D in the past.
It will be interesting to see how fast Tascam fix the USB interface problem, especially as they are advertising it as one of their main features. Its not a major problem for me as I have a perfectly serviceable dedicated computer interface set up, but is a bit poor if it adds another layer of complexity for first time users, or folks who want to lead a simple life.
The firmware releases seem to be mainly concentrated on operational stability, which is quite important to get right.
It will be interesting to hear more as people get to use it in the field, what it is really good at, what doesn't really work and maybe something that persuades me to scrap existing kit and use this as a replacement, i.e. creating space and making my life simpler!