The topology of the Fuchs is pure Dumble. The difference is that there is less padding between stages 2 and 3 (IIRC). So it's a high-gain Dumble.
Personally I don't think the Dumble topology lends itself to that much gain but I didn't design the amp so...
If you like the base Dumble sound but want a little more gain without the fuzziness of a Fuchs try the Carol-Ann models.
Yeah, IRL, Fuchs are basically just a Dumble ODS with (IIRC) a 47nF mid cap, as opposed to the 10nF value. So the Fuchs should have less low mids in the tonestack, otherwise it's a umble ODS. I believe some of the Fuchs also have a variable HF roll off, instead of fixed snubber caps, to roll off highs on the OD channel. If that HF rolloff isn't utilized the highs could start getting fizzy at higher gain.
I disagree with the dumble topology not lending itself to that much gain. In many cases, we know the ODS as a lower gain amp, because many people set the (internal) OD trimmer (between 2nd and 3rd triodes) rather low, which keeps the gain tame. That's also how some of the more popular Dumble users (Carlton and Ford) use their amps, not very gainy. But the circuit itself has a ton of gain on tap. It will be more 'Polite' than a Marshall or a cold clipper amp like a SLO, but the gain is definitely there, and IMO can hang with the Mesa Mark series, if you crank the trimmer up on the real (or clone) amps, especially what's known as the 'High plate' circuits.
Remember (or for those unaware), this circuit has 4 cascaded triodes, plus an optional FET boost on the front end, plus a tonestack bypass, for more umph. To be fair though, using the tonestack bypass (PAB) with a lot of gain can make for a mushier sound that can be a bit to 'thick' for chords, but great for compressed single note leads. Keep in mind, these circuits weren't really intended for metal tones, so the bass is much less rolled off, which may not lend itself to the best chord clarity when used at super high gain for rhythm stuff.
Another tip is I would run the master a bit lower. These are not intended to be power tube distortion amps, even though that's achievable, the sound works much better with the power amp remaining clean and tight, and the clipping coming mostly from the preamp.
You can also dial out some of the fizz rolling off some of the highest frequencies, which is basically what the 'snubber' caps in the OD stages do on the analog amps.
Just for poops and giggles. Sonny Landreth getting awesome chord clarity with a searing overdrive tone on his ODS. I believe this is a bluesmaster circuit, IIRC.
Jimmy Herring, with what I was told was a Fuchs ODS and Fender bandmaster. One of the least fizzy high gain tones I've come across.