Ok, so enough is enough...
I finally went ahead and bolted everything together and took her for a real ride for some real world testing... AKA let the components really heat up vs this 15min at a time thing in the garage.
So, here's what I found... everything is basically the same as it was before!
All connectors cleaned, WD-40'd, etc... with the proper sized battery in.
But, paying a little closer attention than my previous rides, I did seem to learn something. Here's the breakdown:
At the beginning of my ride...
13.1 - 13.4 V @ throttle.
Roll off, and things would gradually climb back to 14V
If fan would hit, @ Idle, voltage would sit at 14V, @ throttle it would sit at 13.1 - 13.4V based on RPM. (This is different than my initial ride here, so I guess cleaned connections did help)
But, when things started to heat up, inconsistency set in...
@ Idle, things wouldn't always climb to 14V. Sometimes it would stay in the 13.1 - 13.4V range. Under power, I would still get these figures, but it was not a consistent DECLINE (read: voltage has always dropped as RPM increased) as it was before. It was all over the place. When the fan would hit, voltage would drop to 12.8V, wether @ idle or under power. And, I took it one step further this time, I let the bike sit @ idle with the fan on. 12.8V lasted for a while, but eventually started to flick to 12.7V. This lead me to believe it was draining my batter (which I've been very careful to keep charged @ max.)
And some other things I have learned from testing and more thorough searching..
Voltage directly from the stator would read 14.2V - 14.3V @ idle during garage tests. But 14.0V @ the battery (or the positive post and engine ground.) Theres definitely some resistance in the system, and from looking at the wiring diagrams, I am surprised that direct VR output snakes through such a complex system before finally making its way back to the battery.
One other thing I learned from from following the wiring diagram for the 07-08 990 EFI starter diagram... I don't have any continuity to the switched ACC circuit @ the fusebox, from the VR on either + cable. Everything else was fine... maybe I tested something wrong?
And finally, I also managed to find one other post on here where someone had stated the output from the Stator should read around 75VAC on all three phases. Problem is, no output RPM was mentioned. I'll take this to mean that my consistent 65VAC @ 5K RPM across all three phases means my Stator is good. Especially with no grounding found.
So, what's next??
Well I'm throwing my old battery back in for the trip home.
Figure if I'm going to kill one of them, it might as well be the smaller 8AH one, especially since it's seen some stress.
I'm also going to be ordering up a new VR. This is the only thing left that I feel could possibly be wrong. Torn right now between Rick's Mosfet, or a Shindegen Mosfet. Right now I'm leaning towards the Shindegen route, and replacing all my connectors with it... assuming it bolts up fine. The Stator to VR connector will definitely be replaced. Haven't yet decided if I'l going to earth the VR in the same place, and connect the positive to the same position either. If I don't connect both + & - from VR direct to battery, I'll definitely be updating the existing connector to the harness with something sealed as well.
Will keep this thread updated, in hopes this will help someone else out.