I would try a combo. Usually, it is the safest bet.
Since upgrading on Tuesday night, My mail has been crashing every time I try and compose, and/or, send an email.
Also, the hard drive is running continuously, almost as if Time Machine was running or it was defragging.
And, some programs, i.e. Second Life, just freeze on start-up.
(Imac 2009, 27", as well as MacBook 13" 2009)