I've had a epi custom and an epi standard.. Agile is much nicer.
I've owned a Gibson Studio (you can see pics of it on here) the Agile still smoked it.
I'd say it compares to the Gibson standard but probably not as nice fits and finish as the gibson... not that Agile isn't good.. I would just expect the fits and finish to be a tad bit better on the $1xxx guitar. I'm willing to wager that the Gibson pickups might have the slight edge as well.
Never had a Douglas, but I did have two SX guitars. GG1 and GG2. The GG1 was like a B.C. Rich Mockingbird and the GG2 was a explorer knock off.
These guitars are HEAVY. Like 11ibs! The guitars setup from the factory sucked, the pick ups sucked, the tuners sucked... but overall the guitar was a heavy slab of Mahogany with a set neck.
All n All, I'm calling it a good project guitar.
you can see my youtube user review here:
http://www.youtube.com/watch?v=9lieFlLqHYY