I just bought the DTX400 kit a few months ago. As a non-drummer, I really like it. It does have USB MIDI out, and you can use it to trigger samples in drum software. I use it to drive EZDrummer, and it works great. The pads feel great to me, and they have adjustable sensitiviy/velocity curves so you can adjust them to your playing style. The triggered MIDI notes are fully programmable, so you can set any piece of the kit to output any MIDI note.
It does have a few flaws, but not quite deal-breakers:
- the arm upon which the hi-hat and snare pads are mounted uses a thumbscrew to keep it secured in place. It's just about impossible to tighten this enough so that the snare pad doesn't start drooping after a couple of songs. So it needs to be loosened and re-tightened pretty frequently. And when you tighten it, it's one of those "use both hands, grunt, and tighten until you think it's going to break" kinds of jobs.
- the hi-hat controller is only open/close. No gradient or half-open position. At least that's how it behaves for me using EZDrummer. Maybe another sequencer would be more accepting of the hi-hat pedal position. I end up using the mod wheel on my MIDI controller keyboard to control hi-hat position.
- no expansion possible on the "brain" module. All of the input ports are occupied by the pieces of the basic kit, so you can't add a 2nd crash or another tom or anything.
- the pads are all single-zone. No chokes on the cymbals either.
All in all, it's a good quality kit, with very nice pads, but it's definitely entry-level when it comes to features. It's a great addition to my little studio, but it does leave me hungry for just a few more features.