This is beautiful. I often find that people underestimate the level of detail and attention required to give minimal arrangements like this one a good sense of groove. It's easy for them to sound robotic and uninteresting, but I feel you've avoided that pitfall. The reverb on your melodic elements is silky smooth and really lovely.
The only thing that stuck out at me was the bass sound- is it live, or not? Its performance sounds pretty dynamic, but on a timbral level a bit static. I'm being extremely nitpicky, but I have to say that eventually I found it a little fatiguing.
On the whole, an extraordinary piece of work. Thanks for sharing! :o]