If the irradiance caching works, it won't take all night to render. Looking at what you said about the gather node's workings, coupled with the irradiance caching; it looks like they maybe trying to implement Final Gathering, which really only needs about 500 rays for production quality. Anything over 1,000 rays is insane. The cost (in render time) to return (in quality) ratio just isn't worth going any higher.
What kind of GI does Poser7 have hidden in it?
Is it photon mapping?
It would almost have to be to properly implement the Monte Carlo. With the Poser nodes, you could probably add various formulae to the Markov chain's probability sampling; and have a native MTL renderer. That would be a serious upgrade to the rendering quality, for the more patient users.
Maybe they just didn't get all the bugs worked out in the rush to put out a new version. That always seems to be the case with software.

Friends don't let friends use booleans.