Mode switching through brown-out detection is not planned so far. This would depend on the specs of external components (namely, the buffer cap) and right now I'm trying to keep this dependent only on the micro controller used.
Do you know at least how they do it? According to a brief glance through this http://www.atmel.com/dyn/resources/prod_documents/doc1051.pdf, it seems the brownout reset would be triggered regardless. So I presume the program counter (part of general registers?) is retained through the brownout so they can discriminate by the entry point after power is resumed?
Also, where did you get the right clip? I think I have a wider/larger one somewhere but it might not fit on that circuit/pitch. I haven't done any real electronics stuff in a while.
As for picking modes, a big list of fine pwm ratios (you can stack them more densely in the eeprom, or just calcuate them) in programming mode that you can pick up to 3 from (using a n-click UI you already have) would be really nice. For example, I can envision doing the 6click to get to programming mode, clicking through the many modes, and 3clicking to pick out up to 3 modes consequtively. Since you write to a mode slot in eeprom and increment every time, it's safe to stop halfway through to re-pick just the first mode so it's not tedious. You can even stack on SOS modes in the programming phrase but that would still spill over 1k unless it was optimized a bit more.