All the MBP's are professional products, I used to have a 990, the base model, 13" one, that was fine, plenty of resources for everything I wanted to do, but I got the oppertunity to upgrade for free, so, obviously I did.
When Apple say you can get 7 hours of battery out of these, they mean it. I take it to college with me every day, and have never taken a charger with me. I always return home with plenty of juice to spare too.
I wouldn't mind the 15" model, but then again, I don't know, the 13" is a really good size, big enough. I did look at the 15" but I'd have to get the MB986, the one with the 9600m, so the increased cost precluded me there. The 13" serves me well though.
Edit:
As of today, I now have 8GB of RAM in my MacBook Pro