The MicroKorg is a great piece of equipment, but it's also prone to aliasing problems at the upper end, which shouldn't be present in the Monologue since it's all analog.
The MicroKorg also offers different features: FM Synthesis and a Vocoder. The Monologue has a full 16 step sequencer, wheras the MicroKorg has only an arpeggiator.
For this price point I think a lot of mucisians are going to find the Monologue is a good value. It isn't far off the MiniBrute which came out at $400 and has less features.
The aliasing can be a bit annoying indeed. You can really hear it when slowly bending a high lead. I don't think it uses band-limited waveforms. But for bass lines it is absolutely fantastic!
Given that it has digital memory I fear that live-twisting on the Monologue also will show artifacts, unless they increased the resolution a lot, but at least if you leave the settings alone it should avoid them. Having a sequencer compared to "just" the arpeggiator in the Microkorg is also nice.
But IMHO it's more important to look at the wider market: There have been tons of small-ish analogue synths in the last few years, in all sizes and price-points. On one hand, that shows that market interest is there, on the other it really will depend on how it compares to those to decide if it will be a success or not, since there are tons of alternatives.
Something I still wonder though is how serious this microtonality thing is. Is it more of a gimmick or it there a serious demand for it?