Two Sundays ago I visited JGR. My delayed response is mainly because of overtime hours spent at work, and I've also had to prep for some sub gigs. Anyway: it's always a great hang with Jonathan and the family, but this is TalkBass and there was a lot going on in his Skunkworks lab.
Item #1: the Saturn V. I'd heard the videos he posted of the final version, but it was fun to A/B Saturn V with my VHF700 in person. They are certainly similar, but JGR tweaked the Saturn front end for a bit more "heft" in the lows and clarity on top. There are a few other changes such as features added/removed, adjustments to EQ points, etc. The tonal differences aren't night and day, and JGR demonstrated that the Bright switch on the 700 would get me in the ballpark of the Saturn's clarity. I've been perfectly happy with the VHF, and rarely use Bright because I often use dirt. That said, the REAL difference between the two amps happened when cranking the Saturn V into a cab that could handle its output. Which brings me to....
Item #2: JGR's sealed 6x10. WHAT A MONSTER. As noted previously in this thread it uses ceramic drivers but weighs only 64 pounds. Compared tonally to my NV610, the JGR610 has a bit more on top and down below (that was confirmed by an A/B with JGR's NV412). I can't really speak to volume differences between NV610 and JGR610, but Jonathan cranked Saturn V through his 610 and it seemed to shake the foundation... unbefreakinlievable! That's credit to both Saturn V and JGR610. It actually reminded me of when I was able to crank my old CA9 through the NV610
Item #3: Gasoline V2. I didn't bold it because JGR said he wasn't staying in the pedal business, this was just something he did for fun. I call it Gasoline V2 because it has a similar layout and features (e.g. 3-position tone switch) of the original Gasoline, but it's noticeably different: it's more of a bright box (voiced from hi mids thru treble) and has less gain and mid punch. It was definitely fun to use: had sizzle that could be reminiscent of SABDDI Presence or B7K Hi Mid, but without mid cut.
There are a few other items possibly coming down the pike. He's kicking around ideas for new speaker cabs... possibly a sealed 4x10 for those like me who (sadly) have little use for a 610; he might also update his tall 2x10 cabs. He found a soft-dome mid that he might use in place of the tweeter in his Wunderkabs (etc) -- but the tweeter on the Wunder sounds really great, not "plinky" or anything, and the differences between those two drivers are subtle. @JGR, please let me know what I'm forgetting!