Elektron Musical Instruments

I'm contemplating a Machinedrum, but I have a couple questions:

1. When recording parameter locks, can you do realtime recording so that you can turn a
knob 
while the pattern plays and record a series of pattern lock values?

2. How well does the Machinedrum work as a sound source when controlled by MIDI
controllers? 
For example, how much can you control via note velocity?

3. Has anyone done a comparison between the Machinedrum and the Waldorf Rack Attack?

Thanks.
Mark