That looks great! There's lots of fun to be had here, I think.
The Dragon arrived today, and to get things started, I installed Atmel Studio (Windows only, of course) and soldered up some headers and a 28-pin socket to do some HV programming. Success! With my new god-like powers, I can set and reset lockbits, SPI_EN, or any other damn thing I feel like. ]
Bwahahhahhha! Mere mortals, tremble and fear!
I did find that the Dragon is indeed finicky about its power supply. First I tried just plugged into the laptop via a USB cable. No go. The laptop didn't recognise a device had been plugged in. Then I got out the powered hub. Still no go. Uh oh.
Then I replaced my USB cable between the Dragon and hub with a shorter, better quality one. Success! But a near-run thing. I was just about thinking of sending it back as a dud.
So even a less than first-rate USB cable can make a difference with these guys. Picky, picky, picky.
But once I got it working, it was all sweetness and light. I might experiment a bit more with Atmel Studio, just to get a bit more familiar with it, and then I will look at getting it debugging on an Uno. I've got a specially prepared one that has had its "reset-en" trace cut today, just for the occasion. (It was a bit of a cripple anyway, with a no-op 8u2, so it wasn't communicating on the USB in an case. Now, it has a new career! Actually, now that I think of it, I may have another go trying to resuscitate that 8u2 with the Dragon.)
I'm looking forward to debugging some code on this set-up with peripherals attached to the Uno. Once I get this set-up, I can see some real time-saving here.
What are the 6 lines of code needed to get avrdude able to work under the Arduino IDE with the Dragon? It's just for SPI programming mode, I'd guess, or can it be configured by avrdude options to do HV programming as well?
Anyway, thanks for your help. How come lots of people aren't doing this???