Me either. This is the single best improvement I've made in the last 4 to 5 years. My MBP is awesome with this X25-M. I have adapted myself to use this little 160gb space very confortably using some external storage at home. This is great! I sure do recommend this to anyone!

I have an 80 gb intel x-25m in my 13 inch MBP but I also took out the superdrive and installed a 500gb live in an enclosure in the optical bay.

Yep, it is off when it isn't and use. It does affect battery a little bit but I have found it be negligible.

How does that affect heat and battery life? Does the second disk switch off when not in use?