The 1000 has new models, new "AIRD" models, the 500 series effects, etc... But yes, the same basic UI. I do major editing on the computer, or you can bluetooth with your phone.
The way I see it, programming is programming, gotta be done one way or another.
Good luck with it, I wasn't trying to talk you into it, just saying that it is in fact a step up from the 100. Of course, you already seem to have a lot of pre-determinations, so hope if works for you.
I've played it for a few hours now. I'm 90% certain I won't be keeping it, mostly because whatever marginal improvement in sound quality is not worth the extra headache imposed by the UI. When it comes down to it, all the icons and text on the screen are about 50% smaller than on the GT100. They crammed more information on the display, but made everything smaller to do so. Which means I can't read them unless I'm right on top of it. With the 100, you can see what everything is from a distance.
I haven't tried all the reverb/delays /acoustic sim, and I'm certain those are ALL BETTER than the GT100. It can switch a 3 channel amp (the GT100 can only switch two channels). It has FX spillover. It has many more EQ blocks and flex blocks. It has an extra set of dividers. This has enough power to build some really complicated effect chains. It can load IRs.
What I've been focusing on is the amp models and the underlying modeling tech. That is what is important to me. Everyone on TGP was raving about how they "dumped COSM" and how the amp modeling is so much better.
I am pretty sure I know what the "AIRD" technology is. In the GT100, buried in one of the flex blocks is a "Tone Modify" block. Within that block there are three resonance processors. Resonance1, Resonance2, Resonance3. They allow you to adjust overall resonance, low, and presence. (I always have this turned on in my patches.)
The GT1000 AIRD amp, they included a resonance control in the amps themselves. And when you play them, they have more low extension and thump than you get by default in the GT100.
There is a sag control, from what I can tell this is identical to the T-comp in the GT100.
I'm going to say it, the underlying amp modeling tech is COSM, its virtually identical to the amp models in the GT100. (Given that they dropped/renamed/shuffled models to obfuscate this.) The X-Mod amplifier, in fact all of the X amps sound like variations of the Powerdrive model with various resonance processors.
I'm not detecting any improved touch sensitivity or dynamics in the amp models themselves. I'm not saying they aren't marginally better, and I haven't played with them enough to know them inside out, but I'm not getting sounds that are better than what I have dialed in on the 100.
I would say that they are much easier to dial in for metal as they have a good degree of cabinet thump by default.
What they did was integrated the resonance processor into the amps themselves, and I presume that effect is also modified depending on what kind of playback medium you choose.
Anyway, for someone who wants to be a mad scientist and devise complicated chains, or who wants the 500 series effects, or a smaller footprint, this would be a great upgrade. For me, I care about the amp modeling and the user interface. The GT1000 is rebadged COSM modeling and the UI is very similar except everything on screen is much smaller.