Is it just due to practicality of smaller/lighter/simpler, or due to preferring how it sounds in live situations?
I've been tempted to buy a used D-Moll a few times as they can be fairly reasonable in EU. I've seen it called a "Mini Herbert", "Einstein successor" and more but am not quite sure where it actually sits.
I used to have a Diezel Einstein and I loved how it sounded but hated how stupid its channel setup was - 3 equally great sounds on ch1, ch2 mostly unusable for anything that isn't high gain lead because anything past 10 o'clock for gain was already "you're just adding more noise".
Well I love the way the D-Moll sounds, fundamentally. The D-Moll has a really thick and meaty distortion tone, and isn't thin in any way whatsoever.
It is
kind of like an EVH 5150III 50-watt head, without the annoying issues. I don't mean tonally, I just mean in terms of functionality - tonally they are very different from one another.
So the D-Moll shares an EQ with channel 2 and 3, much in the same way the EVH shares one for channel 1 and 2. However the D-Moll just seems really well balanced, and the EQ you setup for channel 2 seems to work really nicely and naturally for channel 3, and vice versa.
It also has dedicated gain and volume controls for those channels, which the original EVH 50-watters didn't. So you don't get into these situations where channel 2 has the right amount of gain but channel 3 has way too much; whereas on those original EVH's you'd setup for a great tone on channel 2, and your cleans on channel 1 would kinda suck.
So that's one thing.
I wouldn't say weight is a factor. The D-Moll is almost as heavy as any of the other amps I have. The lightest amp actually is the Dual Rectifier. It is noticeably easier to pick up and carry.
It has midi, which means switching channels from your multi-effect is really really simple.
4-cable-method with the amp is really transparent too, the loop is really good.
The mid-cut feature sounds really nice. Most people think mid-cut means no means, but that isn't this at all. It is more of a focused cut in the lows, which tightens things up.
So.... with a Helix and a D-Moll, you can really do a lot. I would have it setup with 8 snapshots; two rows of 4. Where the amp switching was the same across the bottom row as the top. The only difference was the top row brought in effects, and the bottom row was just the amp with only gain-stage effects.
Clean (channel 1)
Crunch (channel 2 - with the 'send' set to -12dB)
Low gain rhythm (channel 3 - with the 'send' set to -12dB)
High gain rhythm (channel 3 - with the 'send' set to 0dB)
I would also bring an EQ in and out to tighten up the lows and boost some highs going into the front of the amp, but only for the gain channels, not the clean. So I could get a whole ton of tones from the amp.
But the last album I used the VH4 and Fryette Sig:X in the studio, so.... I mean, my mood changes with the wind, so I wouldn't put too much stock in what I say on this topic lol.
I might do a shoot out video between the Diezels.