Done a lot of searching around and this seems to be the smallest keyboard with a mod/pitch wheel and a decent number of keys. It's surprisingly playable as well once you get used to it. In case you can't tell from the picture, the keys are around 66% size btw and the whole device is 56 cm long. Maybe if you had wide fingers you would struggle, I dunno. I use this when I just want to mess around with Ableton Live or a software synth and I CBA connecting up my heavy 61 key controller, or I don't want to sit as a desk. And it's fine for inputting tracks/clips as well, as long as they're not full range piano pieces. Keys feel nice, velocity sensitivity seems to work fine, wheels and transpose octave buttons seem fine. You also get vouchers which get you money off the Korg Legacy collection (6 software synths), EZDrummer (drum plugin) and Ableton Live Intro.
One thing worth mentioning, you do need to install some Korg software if you want to change velocity curves or any other midi settings.
I wish they did a 49 key version with 8 sliders/8 knobs/8 track buttons, but they don't. Seems there's a gap in the market there for someone to make a small keyboard with more functionality. I guess I will have to pair it up with a Korg nanoKONTROL 2.
Bottom line though, it's small and very light weight, 37 keys is better than 25 IMO, it has the mod/pitch wheels, and it plays well.