So, we have made an offer to a candidate, and he will be coming on board this Monday (it's Friday today).
After some review by him we will make the final decision between ACS & OpenACS in the next 1-2 weeks.
I've been having all our current developers train on ACS, but it's clear there won't really be much difference if we switched them to OpenACS if that became our ultimate decision.
I'll post more updates as they come.
Thanks to everyone for their very useful input.
-Hawke