Wow, truly impressive
I'm running a Late 2006 MacBook Pro and when I first installed the Momentus XT I was a touch disappointed; launch times hadn't significantly improved, it ran loud and hot, and made a consistent beeping noise. I kind of abandoned using it much for a while after that.
Enter yesterday, when I remembered the youth of the product and a possible revision that could improve things. So I checked out the model number, saw an update, but then noticed it wasn't necessarily a mac oriented install. I proceeded to download the recommended file anyways, and did a bit of a search to make sure that a mac install was straightforward enough. I saw some ominous signs along the way though, such as "if your computer loses power it's all over", so I became pretty hesitant. The disc booting methods were unfamiliar as well (using DOS?!) but with this thread's first post I became confident that it was simple enough. And to my delight, I didn't even require any "forcing" and the firmware was downloaded within a minute *phew*.
So anyways, I was running S23 and S25 so far seems to have sped up the boot time, browsing and Safari in general are liquid (I'm also running ~3 gigs of RAM). Also, the beeping issue seems to have gone away, which is great as I don't know that I would like to use the labtop very much any more with it (right after upgrades even, heh). I noticed there was an issue with slight hiccups while running StarCraft yesterday, so hopefully those have gone away too. If so, I highly recommend. I was a bit worried that the bus limitations would be too much, but here I am, quite pleased.
P.S. A small note about the install/boot process. The disc selectable is named "Windows" (Referring to the MS-DOS I'm guessing), so just heads-up that it's a-ok and contains the dedicated firmware install to use. Yes, for your Intel Mac (regardless of whether or not you're using BootCamp).