A few months ago I got myself an SSD. Agility 3 OCZ 120GB. Moved my OS over to that and reaped the rewards. As well as the noticeable performance increase, the WEI jumped up to 7.4.
Last week I got me another one, along with some RAM and a new GPU. Now while my FPS is now saucy and performance is performing mighty fine I noticed my WEI for the Primary HD has dropped to 6.9 .......
If you are comparing a "fresh" install WEI with a later one, yes the drop is reasonable. Some of the diff could be accounted for in the percentage of fill and Number of blocks marked used and not yet cleared.
If you see NO day-to-day difference in performance - ignore it.
I also have two 120 gig Agility III's.
I only recommend them if the Price is right - Well below say the Curcial m4, Samsung 830s.
Reason. While they are label SATA III they do not perform any beter on SATA III than when used on SATA II. Reason I dub it a Sata II SSD dressed as sata III.