*Scratches chin* interesting info.
My mind is trailing a bit. I'm thinking over all 9400M will have higher battery life, BUT if I try to run a game on both systems.
What do you mean by "both systems"?
As of now, Mac OS X does not allow any hybrid use of the graphics cards, either it uses the 9400M or the 9600M GT.
Something like 5-6 hours on the 9400M and perhaps still 5-6 hours on the 9600M GT, considering it's already using that power for graphics anyway.
You will get less battery life with the 9600M GT any way you spin it, even if you don't do any graphic intensive tasks.
Also--the mid range MBP is faster, and although I have to deal with shortened battery life, my experience with laptops is that when you have high battery life, you have to wait long for things to load ANYWAY...
That is not true with MBPs.
Mac OS X uses the full capacity of the CPU and GPU, even when on battery power.
The reduction in processing power and the resulting slowness might be an experience you had with older laptops and their handling of CPU resources.
But when a Mac laptop does need 100% or 47% or 14% CPU power while on battery, it gives you that power anyway.
It just does not need 100% or 47% or 14% all the time, only when needed.
It's like with your cellphone, while it is in standby (on, but no activity except keeping the signal) it lasts longer, but as soon as you interact with the phone, SMS, call, gaming, the CPU is in use more than when in simple standby mode, thus the battery gets drained faster.