Wow! Thanks for posting those YouTube clips. A picture (or in this case, a bunch of videos with sound) are worth $1000 bucks (or in this case, $4000).
Allow me to play devil's advocate for a moment, if for no other reason than to dot all my "i"s and address all questions before I take the costly plunge myself (T/B/A once some money shows up):
1. I watched all 11 videos. I'm a bit surprised that there are virtually no clips showing it's polyphonic capabilities. The only instance I found was in video #8 at the tail end, where he plays a couple of chords high up on the neck. I'm wondering if this is just an oversight or if the bass has problems tracking more than single notes below a certain range, as the chordal work he does is above the 12th fret.
2. The slapping video is impressive in that he shows how well and fast the bass can track. I wish there were some more smoking videos of speedy, dexterous playing to further drive the point home, however, and I'm also wondering if rapid tracking and transient response with a sharp attack are required to achieve those kinds of fast tracking results. I know with pitch-to-midi technology (such as Roland's GK/GR systems), the sensitivity can be adjusted accordingly for how you intend to play the part (i.e. hard touch, soft touch, tapping, etc.), which is also needs to be adjusted within your sound processor/midi keyboard parts in order to achieve the best performance results. Sound patches with a sharp, short attack/decay, such as a snare drum or marimba, will almost always track better than a patch with a long attack/release, at least in the world of pitch-to-midi recognition (though flubs won't be as well-concealed as, say, a string patch with a soft attack/long release). I see in other videos posted that he can clearly slap, pluck, and hammer on/off to trigger his sounds, but in the only other instance where he shows some fast playing the particular patch he chose doesn't really do justice, since it's a low dubby synth bass tone with a long attack/delay that sounds mushy when he tries to fly on the neck. Again, probably not a flaw in the midi bass itself, but just the wrong choice of sound patch to exemplify it's capabilities.