I just replaced my 5400 with a 7200rpm drive made by Hitachi 7K100 80 gig. I don't know where you got the 10% increase between the two, but your number are crossed. 10% is 4200 to 5200. Where 40+% going from 5400 to 7200. A 7200 is like going to WD 10000 Raptor drive in a desktop.
I have not noticed any heat change. I would suspect the the battery life is reduced. As for as performace, un surpassed. Boots in 1/2 the time, all programs load noticably faster. All 2.5" drives are more expensive than their counter parts. Seagates have the best warranty (5yr), Hitachi has the best performace (80 gig $160) . As for battery life, It takes more to write than read. But if you are spending all of the time loading and moving cache files because you are low on ram. You are defeating the process. OS X need a minimum of 1gig to run cleanly. 4200 rpm drive are suppose to give you the best battery life, only if the rest of the hardware allow it. If you are spending 1/2 the time waiting fro somthing to happen, extended battery life is required. But if you are not waiting productivity goes up.