+T for coming to that conclusion. Good work!
Don't want to rain on the proverbial parade, but FWIW, I tried the same thing and it worked fine... until the operating voltage from the 6v, through the VR dropped off below the JB3's cuttoff voltage. When this happened *during record* (it's not an issue at idle or during playback), the unit froze up and I had to do a hard reset, losing the file I was working on... of course this happened ~1:45 into a two hour set, so I was pissed. I imagine you'll be fine so long as you keep your 6v well charged and don't ever run it down to the wire. For me anyway, having the second creative battery is more than enough power to come home with the goods.
Nothing like a little DIY action, though. Glad you're getting into it.