Charging System Sluggish when hot

Alright guys help me out.
I put a voltmeter on my Turbo Seca dash so I can watch for electrical issues on this 30 y/o bike. I chased down some charging system issues, and now I can't tell if I still have a problem or I'm worried about nothing. The symptoms:

1. I start the bike, and right away, if I blip the throttle, my voltmeter rises up to almost 14V (it's always had an offset from the battery voltage, it reads the voltage at the dash and is cheap, battery terminal voltage is 14.5 at this reading). This is expected.
2. I ride around for 30 min to an hour, and the volt meter is pegged just under 14V <-- Good
3. I come to a stop. The rpms drop below 2500 to idle, and the voltage falls onto the battery. This is expected. If I blip the throttle right to 2500 rpm, I don't see a voltage response. If I hold it there, or rev a little higher to 3k or 3.5k it'll slowly rise until it reaches regulation voltage in about 2-4 seconds.

So the question, is this normal? I don't seem to remember it ever doing this, and it always does it when hot. I'm afraid to ride it longer and end up stranded with melted plugs. What I've done so far:

1. At the beginning of the summer, I went for a ride and noticed my voltmeter wasn't charging. Suspecting my cheap meter, I got it home, confirmed that the voltage was not increasing, then found a melted stator plug (this is why I have the voltmeter)
2. I replaced this plug. I can't remember if I found any other issues. The battery was also replaced around this time, and I figured my weak charging system and sitting on a possibly bad battery tender for 8 months killed it. The new battery has been subjecting to my charging system tests, but it is a 3 month old AGM and it starts the bike no problem.
3. While thoroughly checking the alternator out, I found that the resistance was high in the rotor plug > 10Ohm.
4. I replaced my brushes, the connector in the alternator, and eventually the whole harness, in addition to my rotor (the rotor resistance was about 6 Ohm). I do notice that if I measure the resistance at the plug, it can vary from 20Ohms down to 9Ohms just from turning on the bike. I assume that the brushes can just sit funny when things are moving and result in weaker contact than when the rotor is moving.
5. Swapped the RR for another spare. This did not change the behavior. It doesn't get a bit hot, but the previous one seemed to get even hotter.
6. There is about a 0.8-1V drop between the red wire in the fuse box, and the brown wire. I've cleaned every connector and the ignition switch.

So is this sluggish charging system issue normal when the bike is hot (and I never noticed before) or am I missing something? Do the brushes/battery/ignition wiring/ anything else you can think of sound wrong? I'm ready to spend all day on this bike and I just need to figure this out.

 

After a ride the battery is full charged, at 2500 it may be charged higher than the bikes output so you see no change.
As you go to 3500 the output charges the battery to max, this is the delay you see.
The voltage can't instantaneously jump up because the battery is a load

 

Sounds normal think you are good.

 

Normal. The regulator dumps voltage unless the battery needs to be charged.

 

Alright guys, it looks like everyone was right and I just spent weeks and $200 trying to solve a normal operating condition At least my rotor is rebuild and wiring is new!

For all you're help, I shall treat you to pics of the turbo on Skyline Drive in Virginia, on a 230 mile ride I took yesterday (with many stops for pics and gas, and not a single electrical problem!). Even had to take shelter as a thunderstorm rolled by!