If your concern is performance degradation over time,

I have done following test:

Fill SSD at 99.9%, then write to the remaining region
over and over again with following procedure :

1) Write 10000 1k-sized files
2) Remove all those files

I have not noticed performance degradation over time,
First run 1 minute 9 seconds
Best run 1:03, worst 1:17 over 40 runs.

Given that I'm not a heavy MAC OS user (yet? :), I cannot
affirm this over days or months.

I saw attempts to do TRIM on Snow L, you may know it already:
http://osxdaily.com/2011/03/27/enable-trim-ssd-mac-os-x-10-6-7/
But I have not tried it out.

HTH