Where have you seen reports of Intel G3 (Intel 320 SSD) users having performance degradation? This drive has been out less than a month. Even if you left the thing running drive writes 24/7 since install 30 days ago you would be hard pressed to have even written to each NAND cell yet.
The new Intel drives do have garbage collection in firmware. Whether it is as good or better than Sandforce I think is too soon to judge.
As an aside, everybody is getting a little too worked up about TRIM IMO. Remember TRIM, or the absence of TRIM, only effects SSD write performance. It has no effect on SSD read performance. Only after you have used the SSD long enough that every NAND cell has been written to does TRIM even matter. After each cell has been used without TRIM, write speeds will degrade somewhat.... and this is assuming there is absolutely no firmware TRIM equivalent going on.