Do 7200RPM hard drives get hot easily and use up more energy compared to 5400 RPM Hard drives? (lower battery life) How noticeable are those differences?
See this post:
http://www.mac-forums.com/forums/showpost.php?p=492979&postcount=3
In short, in the real world, the extra speed has no real impact on battery life as far as I can tell, and my experience has mirrored that. Heat is the same deal-the 7.2k drives use, at most, a couple tenths of a watt more power than their 5400rpm counterparts. You will never notice a difference between the two drives' heat output.