Android scenario: Even cheaper? Plug your cut down megadrum into your £35 phone and use your phone as the brain.
Point: cheap phones can be upgraded to Android 4.4+ with Cyanogenmod. I'm actually using a i9250 though which was £105 used.
MIDI usb-host on Android also possible: http://www.mikrosonic.com/rd4-midi-android (Driver behind this which is in your phone firmware hopefully? https://github.com/kshoji/USB-MIDI-Driver )
Android latency: I haven't seen real measurements yet. It seems the app community mostly haven't yet got the memo regards latency being fixed in 4.4. I've tried out a few drum apps and it seems usable... and this was over WiFi which has at least a 10ms delay. Probably 20ms.
Related thread: http://www.kvraudio.com/forum/viewtopic.php?p=5546138 It would be nice to find another thread on this
However, I see angr77 not happy with Asio4All performance so this sounds like a high bar to hit:
http://powerhell.wordpress.com/about/zo ... windows-8/
Phone triggering Toontrack EZ Drummer:
Ingredients for this were low latency Asio driver, wifi midi drum app, loopback midi, vsthost app for EZ Drummer and EZ Drummer itself. Quite an involved setup really! The same thing with Hydrogen on linux and you have a fully free solution. (thanks ignotus for that link!)
Repairs:
Although I really want a Megadrum we already have a DM6 (not 9 as I thought before) at work. Unfortunately all the symbols aren't triggering properly now. All I've done for this is swap a drum pad into the hihat position... seems to work. Taking apart the cymbal... wow I can't believe how simple it is - Piezo... jack... that's it! No wonder megadrum makes so much sense! You could glue one of these on to any surface and get a similar effect - like wood. Interestingly they've chosen to glue the sensor down. I will order another piezo and chip off that glue to replace it... if it breaks again, it breaks.
Vol hihat:
One of the things I really miss on this cheap kit from a real kit is qualitative control on the hihat (for want of a better word). I see i's referred to as 'continous control viewtopic.php?f=3&t=16 here. If it was my own kit this would make me buy a megadrum just for this. I can't see an easy way to add this to our kit without basically starting again...
Hope this has inspired some ideas for someone. Have fun!