It hasn’t been mentioned so far, but I would look at the Roland MC-101.
It gives you a 4-part multi-timbral world of Roland that you can seq from the DT, it’s a perfect companion to the KeyStep Pro, and it’s ideal sample material for the DT. Plus it’s compact and you can use it on its own.
I’d also look at the iPad route, as the bang for buck and sonic possibilities that combo gives are hard to beat… having got into it recently myself I’d say it’s more powerful than using a laptop.
Thanks. I ditched that one in my search for a sampler/Groove box when I chose the DT. Had forgotten about it since then. As a companion it looks pretty good though.
So already doubled my budget 
so I guess the iPad is also a contestant now.
I’m in a very similar position but with a Polyend Tracker.
I’ve got an iPad but it takes me out of the hardware flow and just feels like a less capable laptop.
I’m currently pondering a Modal Cobalt 5s as it’s a compact midi controller + a capable synth. I’ve also been thinking about a Digitone or Cycles but the lack of polyphony on the Cycles puts me off a bit.
I have two of the synths you are interested in.
MicroMonsta 2 is wonderful, MicroFreak is also great but different: 1 part, less polyphony, more oscillators and a much more immediate interface for tweaking.
I think the best thing to do with a MicroFreak is to pair with an FX pedal; it really opens up with chorus/delay/reverb. Your budget can cover that.
Sampling the MicroFreak into the DT would be cool!
Selling my MicroFreak (to minimise my studio) if you’re interested:
https://www.elektronauts.com/t/fs-uk-microfreak-250-ono/173851
This is getting harder and harder. I like the Waldorf for the multitimbre options but since I have ADD (you can also tell by jumping from one synth to another in my comments) and know I will get lost in presets and possibilities without actually creating anything, I am afraid I will never learn and use the full possibilities. On the other hand I am not making actual songs. I just like to play around with sounds and coincidental finds. That’s why I bought the DT and not a MPC
Still drawn to the Micromonsta though. Also because of its size. I like to take my DT around the house and plug it in where I like (I know the iPad is maybe the best option there).
Many thanks for all the suggestions!!!
For all the people who mentioned the iPad. I bought a camera kit for my iPhone to keep me busy. It’s pretty bizarre when you think about what possibilities you had in your pocket all the time.
Will be looking further for hardware though.
In this combination I would use the M:C more for beats and percussion so that I have more free tracks on my DT.
I would like to make more glitchy, beat based music, rather than melodic synth wave or ambient.