OSX Mountain Lion on Mac Book Pro 13"

So, I've read through some forums and they say that upgrading to OSX Mountain Lion onto a Mac Book Pro would drain the battery of it.

I wanted to ungrade my new mid 2012 Mac Book Pro (13 inch, 2.9GHz Dual-core Intel Core i7), but I'm afraid it will damage my notebook. Like I dk, the notebook would get too hot or something. So, I was wondering whether upgrading the Mac Book to OSX Mountain Lion would be a good idea or not?

Thanks.