Well it sounds like you already have most of the problems with inheritance covered. Since you're only planning to use it on the acs_objects and derived tables, it sounds like the wasted effort would be small if it didn't work out.
As far as performance, I was not too concerned about selects from inherited tables, but rather the possibility that indices might not function correctly. Hopefully, your plan will take care of that problem.
I'm ready to start immediately. All we need to do is partition up the work and decide on porting guidelines that are specific to acs 4.x.
Since you and Ben looked at the data-model in detail, did you come up with a new set of porting guidelines for acs 4.x? Generally we already have a pretty decent idea of porting guidelines, but I was wondering if your and Ben's look at the data-model brought to light new issues that we need to address prior to commecing our porting efforts.
