I jumped on the SSD train early on without 6G controler on my motherboards, so haven't had the pleasure to run on SATAIII / 6GB yet, but future proofing is a good excuse to go 6G.
I bought a Kingston SSDNow 64GB for my laptop in December 2009 and transferred it to my HTPC shortly after. My game system is running a Crucial RealSSD C300 64GB as boot for Win7 64 Pro, since September 2010. Married to that are two 1.5TB WD Black in a RAID0 volume of 2.7TB, split into one 2TB partition and one 750GB one. So far I have some 40GB allocated on C:
Samsung "KIES" is in my user folder, which takes up 6GB, pagefile has grown to 8GB as you can see and hybernate wants 6GB as well. Once I get around to it, KIES will be moved.
On my D drive, I have most of my programmes installed, divided up into:
-Games (Steam etc.)
-Programmes (Internet, Media, Tools)
I seriously doubt the sequential write numbers you posted are from same size SSDs. The comparable 120GB Vertex3 scores 415MB/s and the m4 scores 375MB/s in that benchmark.
As to why I think Crucial's M4 is better than the Agility is from looking at many reviews of the M4 that were done after
the updating to Crucial's firmware 0009 and focussing on real world applications. Comparing SSDs has to be done with equal size SSDs, since comparing a 120GB with a 60GB one will always favour the larger one in 99% of the benchmarks.
If I were to focus on write performance, I would let "Incompressible Sequential" write benchmarks decide and go for Corsair P3. Makes sense for people who mainly use iTunes and compressed video files.
Skinflint.co.uk has the 64GB M4 as the lowest price per GB SSD
, under 100 quid. The 120GB variants are close together. Finally, one 120GB comparison (Pre-0009) @ HardOCP