Would it be conceivable for a Droid character to be a Sentinel/Investigator? There are relatively few Force-talents in the tree and they would still be able to access a signature ability without buying into them. This character would likely be played similar to http://starwars.wikia.com/wiki/Russo-ISC

Why not only force talents require the force

If you're willing to accept the drawbacks, then sure, why not. You could, however, also go for something like Bounty Hunter/Skip Tracer or Colonist/Marshal and still play a similar role, but without missing out on talents.

Yeah, just because you want your PC to be an Investigator by IC profession does not mean they must take the Investigator Spec.

There are half-a-dozen or more that could be spun into that role.

I think the crux of the issue is that the OP wants the My City signature ability. And therefore mist have the Sentinel career and a Sentinel specialization. At least, I'm assuming it's My City they want .

So the answer there remains "Yes." You will need to determine how the droid ability that increases staring skills applies when the career you have has fewer than normal, but you can definitely do it.

Although, I might suggest asking your GM of you couldn't take a different career and trade signature abilities. If that's what you really want, why not make it easy on yourself and just swap out instead of trying to fit a mechanical peg into a space-magical hole?

4 hours ago, Absol197 said:

My City signature ability

The Sense Seek force power is practically a cheaper version of this Signature ability.

I think you're thinking of Unmatched Vigilance . My City gives you a Boost to four different amazing skills, lets you decrease difficulty of Stealth and Skulduggery checks for some strain, and lets you find things really quickly. My City is a boss Signature Ability. Sense has nothing on it.

In my opinion, at least.

Actually, that's a typo - I meant Seek! You can find a person or object regardless of current distance. It's way cheaper. In saying that, My City offers some unique options not found in the Seek ability.

The other thing is you have to be "familiar" with the target of Seek, and it doesn't give you the precise location, only a hint or a path, and it costs 2 Force points to use at minimum, meaning it's not guaranteed. Usually good enough for government work, but My City is perfect (as long as the thing you're trying to find isn't plot-protected), and doesn't require you to have much more to go on than the name of what, exactly, you're looking for.

But yes, there is definitely some overlap there . But, seeing as the OP is playing a droid, Seek is unavailable to them, anyway.

To be clear a Droid is able to spend xp on Force talents, including the one to increase Force Rating. They just receive no benefit from owning the talents. It's a tax you must pay if it's in your path to other talents you want.

In this case it is irrelevant since no Force talents are gateways but I thought it worth pointing out.

as for @Absol197's point about the Droids extra skill ranks well you probably stick to the 6/3 free ranks since that's what the ability specifically says. It doesn't say "an additional 2/1 ranks" it says "Gain 6/3 instead".