Consumer Xenons don't SEEM to appreciate significant overdrive. I did a 4 cell Xenon Star on 5AA NiMH succesfully, but it smoked on 6AA.
The 3x123 bulb for the poor man is a KPR112 or M*g 5 cell Krypton Star (although a 5 cell Xenon star might not blow - and a 6 cell would likely be a better beam than the Krypton).
Bottom line, heavy overdrive is best left to the Kryptons or the High end Carley and WA bulbs.