John,

Funny you should ask about the A123's . I fly electric as well and have been using these cells for almost a year now . I've used them in applications drawing almost 60 amps and they work really well .
Most recently I started using them for other applications . I use 2 2s packs for the RX/servos in my new Wren XL200 powered Liebetrau SU-27 . When tested with a 2A load the packs deliver 6.4v . Last night I did a test at 10 amps and still got 6.2V . I haven't tested the amp draw on start up for the turbines recently but did a test a long time ago on a RAM 500 and got only 8 amps . Next start on the XL I'll check . I'm sure the XL200 is a good candidate for 2S A123 because the starter off RPM is only 18k and theoretical no load speed on the Speed 280 BB starter motor is about 28 K at the 6.2 volts a 2s A123 pack would deliver.
While I'm sure it's suitable for the larger motor , a 2S pack may be marginal for an MW54 size motor and a 3S pack would be required for the MW 44 because they need to be spun up past 35k for good cool starts.
I love the fact that these cells are less critical than lipos and can be charged very quickly . I'll do some more testing over the next little while and post my findings here.

Marc