I believe the power supplies for the mk1 are hard to come by these days- that’s the biggest reason I could think of for getting a mk2.
Samples sounds great in the DT and in the MD, but they sound wildly different. I loved the sound of samples in the MD- they sounded crispy.
You can absolutely control the MD from the DT, it’s a great way to apply the more advanced sequencer features to the magic of the DT. One method I would suggest is to midi link the patterns across your machines and use the DT to sequence more constant sounds(kicks/snares/whatnot) meanwhile locally sequence the more dynamic sounds with heavy p-locks.
I’d definitely recommend getting a +drive model. It’s an inspirational machine that will lead you down a rabbit hole. Even if you’re planning to do ALL of your sequencing from the DT, it’ll be useful to have multiple snapshots(currently called “projects”) where you can explore the sound sculpting capabilities of the machine- a few scratch projects to design cool kits, export them, and then import them into the snapshot where you’re going to do your purposeful emissions
The MachineDrum is my favorite Elektron- it’s an amazing piece of kit