Another concern with SSDs involves TRIM.
As you may recall, when you create an encrypted drive, TrueCrypt asks if you want to wipe and overwrite the entire drive and recommends doing so unless the drive already contains only random data. I don't know if there is actually a known security issue with only having your data and not your blank space encrypted, but it is at least implied that this could be less secure. IOW, if you buy a brand new blank drive and set up an encrypted container on it but don't wipe it, the drive will mostly be obviously blank instead of apparently encrypted. At the very least, this leaves less disk space that needs targeted using any given decryption attack vector.
TRIM can effectively do the same thing on an SSD even after it is encrypted. You may write encrypted data to the entire drive, but when you delete something in the OS and it sends a TRIM command to the SSD, that part of the SSD is again obviously blank instead of apparently encrypted.
This is only true for standalone SSD use. If you have your SSDs in RAID, then TRIM is not supported, so this problem goes away. I believe it is also possible to disable TRIM at the OS level. In either case, not having TRIM means the SSD will perform slower, which can be worked around using the "garbage collection" that most SSDs support. To do this, you securely erase the SSD using its internals so it is in a factory state, and then you never write to a part of the drive (say the last 10-20%). With RAID, this is easy, because you set the RAID container size up and the OS doesn't see the rest of the drive. Then, the already mentioned wear leveling uses that space when other data is being overwritten, and frees up the overwritten space before more data needs written. The benefit here is performance gain, but with FDE, it also comes at the expense of deleted/overwritten data sitting on the drive longer since there is more space to garbage collect / wear level across. Eventually all of that data is encrypted too, though, depending on how much writing you do.
ETA: Trim is not supported in any semi-current RAID system that I am aware of. I have not re-investigated this in a couple years and would expect it to be supported in the future.