Im a huge advocate of the Duel HDD mod. A few months ago I was ready to pull the trigger on the G2. When it comes to programs I have about 34Gigs installed at any given moment. Then I looked at all my media. I have over 200Gigs of music, 100Gigs of movies and a couple gigs of pictures and documents. I DEFIANTLY did not want to put out the money to hold all this stuff on an SSD. Then I started looking at how often I use my DVD Drive. to make a long story short, not often.
I ended up going with the 80Gig intel G2, Then did the HDD mod to the DVD drive and swapped out the DVD drive for a Hitachi travelstar 500Gig 7200RPM drive. then when you are JUST tuning programs you can unmount the HDD to save battery. this takes all of 5 seconds to mount and unmount so its easy to do.
This was the best upgrade I have ever done. you can see my MBPs specs in my sig, when im running a few programs with the internet ON via WiFi and the Hitachi unmounted my battery lasts 6.5 hours. With the same programs running Plus itunes playing music, hitachi mounted (thats where my MP3s are) internet on, yada yada yada, My battery lasts 6 hours. With Hitachi unmounted and WiFi turned off, running the same programs the battery lasts almost 7.5 hours.
the Hitachi drive is VERY VERY quiet, VERY low heat and the 7200RPM drive is very fast. I couldn't recommended this setup enough.
BTW, You can buy an external enclosure for the DVD drive you take out for around 30 bucks. This way you DO have a way to run CDs on your MB...
Hopefully I could be of some help by sharing my experience. Good luck with the purchase.