Why would you care about it? I just got 32Gb SSD like this and you know how long it will take me to use it?
TRIM only helps when you to get maximum speed from SSD, in Amiga environment you can get about 1Mb/s or 8Mb/s (I've never seen faster... in my own eyes). So, who cares SSD will have to delete AND write info on this SDD at the same time.
BTW. I was using mSATA SSD with my iBookG4 for about 2 years (much, much more data written/deleted) and I did not noticed any speed deterioration. I would not worry about TRIM for Amiga 
From what I am reading it's probably better not to have TRIM in case you need to do data recovery. It will get a bit cluttered though.
As stated though it's tough to see the benefit if it can never be faster than a CF.
