I've been playing around with this whole landing gear thing for awhile now, trying to master it, but basically just dumping it in all sorts of situations and getting shot down numerous times in the process (best way to learn what will and will not work).
It can certainly come in handy.
There's really nothing like going into a steep, fast dive against a plane that probably thinks you're the average Corsair that's going to try and run away, only to drop that gear, pull a hard breaking turn up, and roll around onto them. If your persuer isn't expecting this they're in trouble. And in the MA, you really wouldn't expect this if you didn't know who you were fighting at first... Kinda like taking advantage of the fact that people expect you to be timid.
On the same token when merging with a Spit or anything really that you'd expect to turn hard at the merge, if you drop it during your merge you can often gain a good angle on it and suprise them them.
Using this tactic does require a fairly good ability to handle the plane at very low speeds, however, as you are basically giving your opponent the E advantage right at the merge, and if they notice, they're going to rope you. However, given the speed discrepancies at the merge (you should be much faster) you can often manage to get just slower enough that you can out or equal merge him without giving him TOO much of an E advantage, and you should still be able to hold with him if he takes it vertical after that, assuming you have a decent grasp of how to control that bird well slow.
Anyway, that's just my thoughts a month or so into trying to learn this new trick.
The Corsair really does amaze me though. It's one of the few planes that really can go into a 1v1 against any other fighter whether you're higher, lower, or co-alt and have many, many options to win. It's hard to say that about many planes.