Lenovo y510p vs y500

Hello mates, I'm very eager to buy a gaming notebook. I'm currently in the verge of choosing between the Lenovo y510p and y500.

These are the specs for 510p (for a price of $1,300):

-
Processor
4th Generation Intel Core i7-4700MQ Processor (2.40GHz 1600MHz 6MB)
-
Operating System
Windows 8 64
-
Display
15.6" FHD LED Anti-Glare Wedge 1920x1080
-
Graphics
NVIDIA GeForce GT750M GDDR5 2GB
-
Memory
16.0GB PC3-12800 DDR3L SDRAM 1600 MHz
-
Hard Drive
1TB 5400 RPM+24GB SSD
-
Optical Device
Ultrabay SLI Graphics - NVIDIA GeForce GT720M GDDR5 2GB
-
Network Card
Intel Centrino Wireless N-2230
-
Bluetooth
Bluetooth Version 4.0
-
Warranty
One year
-
Battery
6 Cell Lithium-Ion


Here are the specs for the 500 ($1100):

Processor
3rd Generation Intel Core i7-3630QM Processor( 2.40GHz 1600MHz 6MB)
-
Operating System
Windows 8 64
-
Display
15.6" FHD LED Glossy Wedge 1920x1080
-
Graphics
NVIDIA GeForce GT750M GDDR5 2GB
-
Memory
16.0GB PC3-12800 DDR3 SDRAM 1600 MHz
-
Hard Drive
1TB 5400 RPM+16GB SSD
-
Optical Device
Ultrabay SLI Graphics - NVIDIA GeForce GT750M GDDR5 2GB
-
Network Card
Intel Centrino Wireless N-2230
-
Bluetooth
Bluetooth Version 4.0
-
Warranty
One year
-
Pointing Device
Industry Standard Multi-touch 2 button touchpad
-
Battery
6 Cell Lithium-Ion


The only major differences, as I see it, are the SLI GPUs and the CPUs. The y510p having gt750m + gt720m + 4th gen core i7. On the other hand, there's the y500 with gt750m x 2 + 3rd gen core i7.

I got the money for both, but I dunno if trading the gt750m with gt720m is worth the 4th gen core i7.

Anyone got any suggestions?
Thanks in advance.