I added an arm rest in my FR.
Am very pleased with it, use it all the time. Storage spare is handy and it gives you somewhere to hide the mp3 player.
I think there are two versions, one with a hole for the aux and one without.
I don't find it gets in the way of the handbreak. The plasic the "box" is made out of does not seem to match the consule, but meh.
It is dead easy to fit. It comes with all the parts and instructions.
Simply plonk the arm rest on top of the consule. Make pilot marks for the screws. Screw down. apply fiddly foam to the bottom. re-apply fiddly foam to the bottom (repeat until bored or no longer tacky).
Then rest arm and look "pimped".