Unless if  you are also bringing in good FullHD external monitors, I think its better to go for notebooks with better screens.
If you are planning to just use the notebooks itself, then the Y500 would be the better choice because of the larger workspace provided by the FullHD screen. But you might need to look into color recalibration tools just to make sure that the screens are alright

The Y580 can also be considered as well since they are cheaper... and since designing softwares probably don't support SLI of the Y500