What do you think of the Samsung MEX controller? Samsung's $600 1TB SSD is pretty tempting.
Samsung drives seem to be the more reliable ones Apple has picked for their hardware. Most aftermarket Mac people have been using the 830 or newer 840 series Samsung drives without issues.
In all seriousness I'm curious why you're interested in larger SSDs.
Doing any work on a hard drive seems slow to me now. I also rarely reboot, so a faster system drive is wasted.
All my laptops (work/home) are 100% SSD storage. The old Mac Pro has a 512GB SSD
fused to a 3TB hard drive. Makes it much easier to work on the 750GB of HD video footage I still poke at, as well as having the rest of the storage feel pretty fast. I don't have to play file janitor, the system does it and keeps whatever data I'm working with on the SSD.
Photos, those definitely benefit from being on the SSD.
And games. Definitely want those on an SSD. I can tell who has an SSD and who has a hard drive when playing Starcraft online. A video from my WoW days showing SSD loading speed caused several people in my guild to go out and buy one.