Since there isn't any thread for Powertech builds I may aswell create it. Been leveling specced into Shield tech (tank) since lvl10 and it have worked very well, little downtime and very few deaths. And have used Mako this whole time. Damage output is nice for being a tank spec and the amount of tools available have made it sometimes quite humorous.
Level 32 spec (http://www.torhead.com/skill-calc#301hMRrdoroM.1)
Strait forward "take all damage reduction" primarily spec. Some notes on what I didn't take
Combust: Didn't find this one worthwhile at the lower levels. But once I respec I will spec into it by taking points from Rail Loaders as I feel I would benefit more at the endgame with 4% damage reduction than 6% extra damage on a skill "little" used.
Neural Overload: Didn't see the need for this PvP focused talent as there is little need to chase down fleeing mobs or to kite them. Sometimes it would have been nice to be able to kite an elite or two but it didn't warrant the point.
Steely Resolve: I filled this talent at lvl 33 and 34 so it will be taken but I found better use for my points in higher tiers during the leveling.
No Escape: PvP talent.
Jet Speed: PvP talent. Again. Have a hard time motivating for myself to pick this in a PvE enviroment.
Level 40 spec (http://www.torhead.com/skill-calc#301hMGrdorogz.1)
Just to display what my filled Shield Tech tree would look like.
Level 50 spec
After level 40 it is the time to splash into the other trees, but I still havn't figured it all out yet. Advanced prototype have some nice cooldown reductions, extra crit on fire and -2% damage taken. Pyro on the other hand have extra damage on Rocket punch, +3% endurance and heat vent on being CC'ed. It's a tough nut...
Flame burst is one of the abilities i use the most, its not cheap nor very expensive to use and it got a low cooldown and decent damage and with Combust it makes it even better.
If you want more dmg out of railshot i would suggest putting a few points in Puncture instead.
This is the spec im gonna use at 50 for tanking 31/8/2 (http://www.torhead.com/skill-calc#301G0GrdorogzZMsbZb.1)
or if im more useful as DPS in OPs ill use this 8/31/2 (http://www.torhead.com/skill-calc#301hMhZMsrbRrfkzsZb.1)
This is the spec I have decided to go for initial lvl50 tanking.
31/7/3 (http://www.torhead.com/skill-calc#301G0GrdorogzZMcbZ0c.1)
I just grabbed the maximum amount of effective health I could get. Depending on the content and gear points may shift towards more threat.