Sounds to me like you wanted the MPK 25, and your only reason to consider other options is that you can't afford it yet. If this is the case, I would suggest saving up for that one.
I've owned or used most of the modern commercially available MIDI controllers around, including the MPK, MPK Mini, and KORG microKEY.
With regards to the MPK Mini vs microKEY:
The MPK Mini has very cheap-feeling keys compared with the microKEY. They're not horrible (pretty standard quality for micro keys), and in fact feel very similar to the keys on KORG's micro-series
before they introduced the drastically different "Natural Feel" keybed a long time ago. They feel like the keys on the microKONTROL (
http://cachepe.zzounds.com/media/quality,85/lrg_microkontrol-f79331b04b74038364bbd46de02628f8.jpg) I used to own ages ago. With that said, though, they're just not nearly as playable as the microKEY's keys.
The drum pads on the MPK Mini have a large gap of air between the base of the pad and the sensor. I assume the pads were built this way to mitigate the inevitable quality control issues that arise with the use of cheap parts -- this way, there's no accidentally activation of sensors which were never hit. I'm accustomed to the very sensitive pads of the KORG padKONTROL and NI Maschine, so I found myself missing notes frequently from not hammering the pads on the MPK Mini hard enough. Seriously, hitting these pads in public hard enough to register a hit causes everyone to turn and stare at you.
The knobs on the MPK mini met my expectations. They're not bad.
The MPK Mini is also very, very portable. The MicroKEY, on the other hand, requires a slightly larger-sized backpack to carry -- it has 37 keys rather than 25. Which reminds me, I hate 25-key limitations. Pain in the ass, even for "non-musician" types -- its just BAAARELY too small.
-Ki
Salem Beats