Isn't the time honoured and only way of resetting all controllers by issuing the GM System On SysEx message?
That's not really the best way to reset channel controllers, unless you really want the full General MIDI function. The best way is to send a Reset All Controllers message (Control Change #121). Sending a GM System On performs other functions at the same time. It is best to use that only when you really want GM, with it's specific sound set, drums on CH.10, etc.
I expect that the MIDI Association will release the spec for resetting all Per-Note Controllers later this year. As pointed out above, it is on our list of priorities.