The 270 is faster. However you could end up needing to run lower game settings because of the 2gb VRAM. If you hit the vram limit you will suffer stuttering or the game not running at all. Lowering game settings can help reduce the vram required. Vram doesn’t give more/less FPS but if you don’t have enough you have a problem.
Try the card friend gives you and see how it does with YOUR games.
It could do better or it could do worse, depending on the game.