Intel controller algorithms that deliver terrific write I/O performance on its X25-M solid state drives actually contributes to them slowing down over time. The issue is fragmentation. The Intel controller combines many small file writes, smaller than the X25-M's block size, into a single larger one thus avoiding unnecessary block erase/write cycles. To avoid the flash wearing out through repeated writes, its wear-leveling algorithm avoids concentrating writes on particular cells by re-mapping the physical cells into logical ones and progressively moving around the flash cells, such that logical flash cell zero isn't necessarily physical flash cell zero.
Check complete analysis:
Long-term performance analysis of Intel Mainstream SSDs
If you have money to spend on SSD go for 10 or 15k SAS. On Long term it will give you better performance and reliability.