Mixed in key?

Clearly this is a hard question. All kinds of factors play a role in that decision, like what you are trying to get it to do, what that is worth to you, what budget you have, etx.

Because the real question you need to ask is “is MiK worht it for ME”. And that is something we can’t answer for you.

As for RekordBox and cue points, at this time it’s only Serato and Traktor. That said, I think it’s fair to assume that soon they will add RekordBox to that list.

Mixed in key. Great program, absolutely, I quickly learned that due to the type of music I play, and the type of gigs I do, really don’t require the key to be matched. So I kinda wasted the money although if I’m mixing house/dance tunes, I do keep an eye on key, but it’s not very often. It’s good If you plan mixes ahead and club/dance music is what you spend most of your time playing.
It’s more accurate than Traktor’s Key detection, if you insist on having key in your tracks, it’s pretty essential, otherwise, I would think about it’s necessity in my setup.