This is looking to be the "cookie-cutter" tanking spec for us Shieldtechs. Since all the talents taken pretty much speak for themselves, I'll just take a look at the thought process that went into skipping the ones I did.
Rail Loaders: Yes, Rail Shot is an extremely powerful ability. However, tanking is not about having strong burst damage. Tanks need to keep up consistent threat generation because if aggro gets lost it can be difficult to gain it back. The only place points could really be taken from to pick up Rail Loaders would be Intimidation. Since Intimidation benefits ALL of our incendiary attacks (Flame Burst, Flame Sweep, Heat Blast, etc.) it provides more of an overall damage (threat) increase than Rail Loaders does, especially considering that the cooldown on Rail Shot is a lengthy 15 seconds.
Neural Overload: Most of our threat output comes from abilities that require either melee or short range. Having targets close on us slowly is not good from a tanking standpoint. Leave this one for the PVPers.
No Escape, Jet Speed: These are nice mobility skills but all of the other skills in their tiers directly impact threat gain or survivability and thus take precedence.
Prototype Electro Surge, Advanced Tools: More good utility skills that are skipped over for skills directly impacting tanking.
Hot Iron: The points for this skill could only come out of Iron Fist. Rocket Punch is already a much stronger ability than Flame Burst and gains massive crit chance, crit damage, and a proc for a cooldown reset from talents in the Shield Tech tree. 8% more damage on Rocket Punch works out to be a much better damage increase over the course of a fight than 6% on Flame Burst.
Integrated Cardio Package: This skill is arguable, but I feel it gets outclassed by other choices. 3% endurance is not a large enough health difference that healers will really heal you any differently. The only time it would really be useful would be if you are in a situation where you get hit so hard so suddenly that you would die without this little extra health. Since I do not forsee this ever happening I choose to pass this skill up for more threat generation.
While I will be running this spec, there are a few alternate ones that could be argued for.
If you want maximum threat generation, you can drop Power Armor for Rail Loaders. This should ONLY be done if you have large problems holding threat or if your healers have no trouble keeping you up (i.e. you outgear the content you're running).
If you want maximum survivability, you can drop Prototype Cylinders and Iron Fist for Integrated Cardio Package. Since this will actually result in quite a bit less threat, make sure beforehand that you can solidly hold aggro without the extra damage from these skills.
For the majority of us, the cookie-cutter spec will work the best. If you want to use a different spec then by all means try it out, but always have a clear cut reason to do so. A tank choosing a spec just to be a unique little snowflake usually doesn't work out well for the rest of the raid.
A note on hybrid specs: Don't tank as a Shieldtech with a hybrid spec. Our end of tree talents are very good for tanking. Empowered Tech is a large increase in our chance to block, while Heat Blast is so heat efficient it actually REMOVES heat on use.