Haven't heard it, but the Woo GES seems to be the more well-regarded design by people who know far more about amps than me.
Also, not sure if you've already searched around, but there are a few multi-amp reviews out there. Tyll's review is here: http://www.innerfidelity.com/content/listening-great-headphone-amplifiers-and-stax-sr-900
AVguide also did a few reviews, although they aren't highly-regarded:
I knew the first reference (innerfidelity) for avguide I just read it and I found it very serious and honest, guess I will decide for BHSE. Thank you very much for your information