The Mega+RAMPS setup (at least from China) can *only-just* run the RepRap Full Graphic LCD. My machine has 5 optical endstops too (I assume they take a small amount of power from the +5v regulator) and after a short time my LCD fades. Adding a heat-sink to the Mega regulator made it take about 20mins before it faded so that was better but no solution, so I ended up cutting the +5v input trace on the LCD RAMPS daughter board and powering the LCD from one of those cheap $3 regulator boards with a multi-turn pot set to +5v. They have 2.5A – plenty for the LCD. I’m also planning to run a Toshiba FlashAir (SD card with built-in WiFi) that are known to be quite power hungry >@100mA over a normal SD card. A different machine I built/own could power its 20×4 LCD from the Mega+RAMPS but the FlashAir wouldn’t power up the WiFi properly until I used one of those 2.5A regulators for it too.