most of us have our own opinions of what a bike will do/should be used for...
many of us have multiple bikes for that very reason...
one for each type of riding we are expecting to do...
no matter what type of bike you have someone will tell you it is not the right one for how you are going to use it, and the next guy will tell you to ignore what the other guy said it will work just fine
and there is always the guy who knows a guy who... but most of us are not that guy who..
the general rules of thumb are rules for a reason..
a hybrid bike is a great all around bike... in the trek line the fx series was their best selling bike for years and may still be for all i know...
some of what has been said I totally agree with..
a hybrid bike is fine for trails.. but you will not go railing down a mountain on it sucessfuly
it is fine for road riding but you are not going to keep up with the A group on group rides..
my wife has a nice carbon fiber road bike and an FX 7.5 hybrid...the FX is her favorite bike for rides on MUTs and roads for rides less than 40 miles...
I am not personally fond of the suspension on your bike, I think it is the one draw back to what you have expressed your main interest is...
for us to really be able to offer much advice of value, we would have to have a little better understanding of your intended use... what do you mean by mountain biking, what kind of trails will you actually be riding? and when you say fitness and speed... are you talking about long rides at 20+ mph or is 13 to 15 mph acceptable to you?
I am also concerned about one detail that was also mentioned, nice bikes have a high theft rate on campus... so maybe a thrift store bike for the rides to class and your nice bike for your evening/morning and weekend rides.