You sure on the 1600x900 display? I had a G750JW for a week and that had a 1920x1080 and I wasn't aware they did a lower resolution screen.
The GTX765m can cope nicely with gaming, I managed to get Skyrim with 70+ mods on top settings with an EMB running, at 60+ fps with no problems at all, and will run things like Tomb Raider on high settings, Far Cry 3 on medium and Bioshock Infinite on Ultra. That's at 60+ fps, if you're willing to drop to 40 then you can turn things up and it'll be fine.
My advice is buy the best you can, the 770 is a noticeable upgrade I've heard. Then there's the 780, which can be overclocked nicely along with the CPU as there's better cooling in the GTX780 version. All other's can be overclocked too, but to a lower extent.
Migrating is a major pain compared to Win7 as you can't clone, but you can make a recovery on a USB, and then use the recovery to migrate to the SSD. The computer has 2 hard drive bays, if you choose a 1TB option then you get 2 7200RPM 500GB HDD's, otherwise generally there'll be one or two 5200RPM 750GB HDD's. So, there's plenty of room to go with an SSD and a HDD, I have 2 500GB Samsung SSD's in Raid 0 (which is very easy to set up). Samsung's generally are the best.
If you get 8GB RAM then you'll have 2 sticks of 4GB ram that can be replaced if you want to disassemble half the laptop, but then there are 2 slots empty that can be easily got to by removing a panel. This means you can have 16GB ram nice and easily, and if you have Windows 8/8.1 pro then 32GB once you replace the 2 harder to get to sticks.
As for the OS, Windows 8 works nicely, and 8.1 even nicer.
As for feel, the keyboard is completely made of Aluminium and is really cool, never gets warm at all under the palm rest at all, and the trackpad is large and responsive. Then you have the 2 separate mouse keys which are a big bonus. Keys are nice too, it's a joy to type on (my laptop is my work horse for Uni work so gets a good amount of use ).
However if you need portability, you might want to consider picking up a tablet for this. I ended up getting a little transforming tablet with 8.1 loaded on it for £350 which is a nice companion.