How important it is depends on how good the garbage collection on your SSD is. A lot of them just do GC when idle and so can go a fairly long time before doing any. Others will clean up as they go, which is a lot better but slows the drive down as it has more to do during file transfer. So yeah depends what drive you use. If you have say an intel 520 then TRIM isnt that important but if you have a samsung 830 for example and it is getting full then TRIM will be doing a lot more for you.