This is the holy grail Al, I have had no real success with it over a few years now. The sonnus does the job but to me it is a very mechanical process, not seamless at all. Sonicsmith had the squaver product which did enable direct pitch to midi (alongside their own synth module), it was good - a definate improvement on the sonnus - but still not there yet. Not sure if their latest product, I'm not sure it's out yet, will really hit the spot or not.
Then there is the midibass and variations on this theme.
Bottom line - it's either doesn't work well or it's very expensive or both. Personally I'm accepting that there are some great options out there that work really well with the bass - the C4, or FI or various pedal combos. Direct control of synths over midi is just not a realistic option though - much better controlled with keys or other dedicated midi controllers.
It does mean that you don't have your bass chops as such but perhaps this is not a bad thing. A lot of these sounds work because of how they are played rather than the sounds as such so there is almost a requirement to change the approach to achieve the result perhaps....
Others may have other views of info of course, this is just my take on it based on my experiences