I own a Microkorg and must say that I'm not really impressed by the sounds the Monologue offers; it seems far too limited and doesn't have that deep punchy bass that the Microkorg offers. And it's a lot more expensive too. It makes me think of the iPhone 5C.
I'm not sure where you're getting your pricing, but the Monologue is $299 [1] and a new MicroKorg is $399 [2].
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.
Seems the Microkorgs have gone up in price over the years. I paid about $250 for it when I got it a few years ago. I noticed you can still get them for $200 second hand.
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!
Microkorg is (especially for something so cheap) a really nice piece of kit and has some fancy features, but especially at the edges of the value ranges you clearly hear artifacts, which don't work for all kinds of music.
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.
Being able to create microtonal scales is the attraction here for me, most synths whether they're digital or analog lock you into standard western scale tuning.
Some dubstep I've heard actually has quarter tones in it. If you find that everything you come up with on an equal temperament scale is boring and familiar, using different tunings and scales might be a useful next step to unlock creativity.
