Which Domain would Be better?

Hi, So I have a project coming up, and I want your ideas & opinions.
I have 2 domains, fps-forums.com and fps.im
If you google FPS forums, there's surprisingally minimal competition, the forums that are there aren't very active, and with time & good content, I don't think would be hard to beat. (Well, behind the amazon link...)

Would it make more sense to run the forum on fps-forums, and use fps.im as a link shortener on fps-forums, or something creative to make it useful?
Or does the .im seem better/more professional/easier to remember?
I'd like to incorporate both if possible, but obviously I care more about long-term success, and I'm completely indecisive.

Still looking for feedback.

fps-forums.com i think that would be very good

Why?
Care to explain?

Just looking for in-depth opinions

I'd say use fps-forums.com and have fps.im as a shorter as you said in the OP.

Hm, that might have to be what I do.