If you can keep the Machinedrum and save up for the digitakt that would be the route I recommend. Like commented already, these two are definitely NOT one for one swaps. You lose and gain from each to the other. I’ve been hooking up the digitakt to everything I can and I’ve been having a blast with everything I’ve done. However, the best I’ve come across and the most fun for me so far has been Machinedrum and digitakt together. I’ve gained conditional trigs, micro-tuning, poly timing, simpler sampling, a different kind of cntrl-all machine and much more to my Machinedrum.
If thinking the other way, I’ve gained the awesome synthesis, sample and resample, addition midi or audio tracks just to name a few for the digitakt. You want to talk about crazy weirdness? Throw in an octatrack with it. Time goes out the window. Forget about limits on lfo’s. I could go on and on about the md and dt paired up almost how the md and A4 paired up or the MnM and ar together are great matches.
I’m just saying I agree with all of the previous posts but consider using them together if you can. Save up for it but keep the one you have. It opens the doors of your older drum machines, synths, samples, noises, Circuit bent toys, pretty much anything you throw at it. Don’t underestimate the Machinedrum because it isnt being produced anymore. There is much more to it than people who never had one knows about.