I actually had a DSL100H and JCM2000 and decided I just preferred the tone of the DSL100H. The JCM2000 ones are killer and built a little nicer, but the depth knob is way more useful to me.
They can definitely be modded, there’s quite a few different mods posted online. I was initially planning to mod mine but I decided I love it as is. Hangs quite nicely against the others - Green channel is very much “stock JCM800” and red is more like “modded plexi”.
You could mod the green channel for more gain, or commonly people mod the red for less as it has so much that isn’t really useable. Modding the green for more gain is likely going to sacrifice the clean sounds somewhat, so it really depends on what your favourite channel is on there.
You could easily tweak the red channel a bit and change the depth knob to affect other frequencies (perhaps on a switch?).