The APC40 is a great controller, but it does basically one thing: launch clips. Hans Petrov decided to improve on this diminutive feature set by writing the APC_64-40 remote script in Python to add new control modes for the clip grid, faders, and encoders.
One of the great things about Max programming is that you almost never have to start from scratch. For my latest project, I essentially frankensteined two of my favorite patches together to make an unholy new device, the APC Mono Sequencer.
I started learning Max/MSP a few years ago around when Ableton and Cycling ’74 collaborated to release Max for Live, a fully-integrated way to add visual programming and DSP to the powerful Ableton Live DAW.