I’ve had my Machinedrum for around 10 years now and I still think it’s one of the best pieces of kit I own. I’ve bought and sold a lot of gear over the years but the Machinedrum always feels like it’ll have a place in my studio, even if I don’t use it all the time. I love how punchy it is and how unique the synth models are even compared to a lot of modern drum synth plugins. I think if you can find one at a good price and in good condition it’s a purchase I doubt you’d regret, provided it’s specific aesthetic is to your tastes and production style. I kinda wish Elektron would make a new one, and a new Monomachine, but I highly doubt that will happen. The unofficial firmware upgrade for the MD expands its functionality quite a lot, definitely worth a look.
I have found myself enjoying exploring the Rytm’s sonic range, which takes a little more work than MD to get out but it’s there. They really occupy two extremes and I like having both around. I think I actually prefer the more performance-oriented design of the Rytm, BUT, MD is just capable of producing sounds that AR never will.
LXR has Kit morph . It’s similar sort of?
So you should check Model:Cycles, Syntakt and even Digitakt (but mostly Syntakt 
) that have all the “machine” concept as a base of synthesis or playing sample. The behavior of the ctrl all you described on Machinedrum is exactly the same on Syntakt (with the same happy accidents).
Does the Syntakt allow you to save the now-changed state of your kit/pattern after function+knob-tweakery? What I mean by this is sometimes in the middle of obliterating my MD pattern after several control-all knob turns, I’ll find a sweet spot I wish to save as a static pattern and I’ll stop tweaking knobs and save the pattern and kit as is to another location allowing for access to both the original and the new pattern for more tweakery. Does the Syntakt allow for this? I bet she does. Dammit! Now I have a crush on the new gear. All the boys like her. I can’t let her know. I think she was looking at me in class. God, I fancy her though.
You’d need to copy the pattern to a new slot, so kind of! No kits but you could also save individual sounds as presets if you don’t want to deal with having to copy and maintain a “template” pattern full of sounds you like.