Hey,
I love your last build, the ST/Pyro hybrid. It keeps all the main damage sources from Pyro while getting a good bit of tankiness and mobility from the ST tree. However, I think you should change one thing in it:
http://www.torhead.com/skill-calc#301GMhrbMboZ0MZfhMrzh.1
I removed the points from Flame Surge and 1 point from Puncture to allow the build to accommodate Prototype Particle Accelerator 3/3. This is one of the best feats for Pyro, since it increases both damage and heat management a LOT (the latter because the target's gonna be on fire 24/7). It'll make up for the damage loss in flame burst/RP crits and the 20% less pen on rail shots (you'll be doing stupid damage enough with them, and they'll be used a lot more). My only decision is whether to spend 2 points in Pyro in Degauss (for anti-CC) or Gryoscoptic Jet Alignment for more heat control.
Thoughts?
Edit: Also, I take it from the two feats you have in the ST tree that you'll be using shield generators over power generators? How does that work out? I know shields have a base 5% to block now, and shield vents bumps that up to 7%, but is there any way to increase the chance without using Ion Cylinder (which is worthless for this build, really, given all the Pyro damage requirements) and the other shield chance feats in the ST tree?