is it a good combo yamaha rm1x + sp 404 for programming chopped breakbeats and making some glitchy drum structures via 16 step sequencer?

or any other advices?

it can work. a trick there that works is that if you sequence on the rm1x, after you are done, turn quantize off on the 404 and record the midi from the rm1x into your pattern. granted it will be out of time with the bpm, but with the resolution of 404, you never know the difference really. this becomes an easy way of having a project be self contained after you're done.

and what about korg electribe es-1?

thr es1 is cool but the rmx1 has a more complete sequencer

Is Rm1x just a rompler or can it sample?

it's a groovebox like the mc303/307/505 or the electribes emx etc: no sampling

it should be noted that it also has a really powerful sequencer- at 120 parts per quarter note its pretty flexible and would allow you to improvise using the real time controls and record the output into the 404=