Not really a good comparison.
A 2MB 7200RPM HDD w/ an avg. access time of <9ms and an 8MB 7200RPM HDD w/ an avg. access time of <9ms are going to run at the same speed. You're only going to notice an increase when you're using files that are too large for the 2MB cache on the one HDD.
I'm sure some applications, games, etc might benefit, but the question was "Will I notice a difference?" No, you probably won't, unless you fall into that %age that thinks they do.