I have a daughterboard TT, making the Speedy mostly a plug-and-play installation, without risking the original CPU (original FPU still gets overclocked though), so I'm going to go for it. I agree that the 16 MHz boost on the system clock isn't huge, but I think that coupled with the new version of Storm, which also speeds up the clock on the TT RAM, it'll be worth it.
There's also a new "Turbo Thunder" in the works, with built in IDE2CF, Speedy overclock support, and 4x flashrom, so that's something else to be excited about.
Now, about that Terriblefire TT60...