I think 16 knobs is enough.Before apc40, there was two other choices:VMX VJ from Codanova and OHM64 from Lividinstruments. Finaly my choice was OHM64 but it was a long delivery time and i choose apc40.The device itself feel rock solid and the knobs are smooth and rugged.Different led colors can be triggered by custom midi messages and knobs will update positions for each layer.The bad is that you have to use another software to customize it and can be very tricky but also very powerful.One button can change the whole layout, so the same knob can send midi on different channels and you can map the same knob to different controls in Modul8. OHM64 it's easier to customize and have a user upgradable firmware, which will include OSC messages soon.Codanova do not make VMX VJ anymore but there will be two other controllers from them in the near future.One specially designed for Modul8. http://www.codanova.com/
I sow some great vj's who use korg nanokontrol , ipad or trigger finger from m-audio, so i think each of those controllers will do the job really well; for me, APC40 is more than enough.