Check here:
http://www.dvinfo.net/sony/index.php http://www.glensound.co.uk/GSTN1.htm http://www.vjcenter.com/english/english_con03.asp (click on the lens hood)
The gain control on the 2000 is OK, There's stacks of gain control, as well a 2 ND filters built in. Of course is has quite wide steps in manual mode. The 2100 has finer control, but in auto they both operate the same.
Of course the usual thing under shooting situations is to switch to auto the get the camera to expose the shot as you want, then switch to manual so the camera holds this exposure. They all operate in this way.
Racking (iris adjustment) the camera as you shoot is not something most people need to do under normal circumstances. But it is better on the 2100/170 that was one of the features Sony added to these newer models.
The 2100/170 have brighter screens, different built-in lens hoods, and operate down to 1lux If I remember correctly (the 2000/150 is 2lux I think). I always run 2000s and 150/170s with the top grade Sony Wideangle lens on so the new shape lens hood is a waste of time. The new screen doesn't bother me, The old and new cameras side by side give very very similar results in all areas. The new models do have zoom demand on the top handle, again not something I have used, as if I am holding the camera low I tend to leave on maximum wide.
So where the 170 beats the 2100 is the XLR inputs, you can by a Beachtek or Glensound box. Good if you want to run external audio kit on dual channels. I personally use a home made minijack to XLR cable to plug in my Pro audio kit. It's worked OK for me. Of course having the 150 would have been good for me, but not worth the extra cash frankly.
Progressive scan is crap on Sonys, But it's not much use on any camera where is doesn't work in true 16:9 too. I apply a film look in post production if I want film look as it often requires grading anyway.
The Panasonic 100 thingy is interesting, but my client who owns 150s as well as digibetas etc. looked at it and says the pictures are terrible, so he bought more 170s instead.
I'd recommend a VX2000, with cash left over for a good wide angle lens (VCL-HG0758), spare battery, decent bag, As well as this:
http://cinetactics.com/mb100m.php