The GT 755M is the exact same as the GT 750M, just has a 2% higher core clock, and has GDDR5 RAM.
The GT 750M has two versions, one with DDR3, and one with GDDR5.
The Y510p comes with GDDR5, so the performance between the two is within ~2% of eachother, you can even bump the clockspeed of the GT750M up that 2% and literally have the exact same chip anyways.
Absolutely 100% get the Y510p over the 410p!
If you find the Graphics chip can't handle 1080p gaming, you can drop it down in resolution for demanding games anyways.
It gives you the option to CHOOSE, and the extra screen space is great. You can watch Hi-Def movies and get the full detail too with Y510p.