It depend on what you play, but unless you play as a pro in competitive fps game, response time, input lag etc is none issue. i seriously doubt you even feel it. i mean console player connect to a TV and i doubt you find them laggy and unresponsive
My pc is connected to both 60hertz 1080 24" monitor and 42" TV. and let me tell you the graphic difference is huge, the TV looks so good it makes the monitor looks like it is running at lower resolution. if you don't believe me try connecting your pc to a big TV in your living room or something as a test.
But unless you plan to use pc for gaming only i will not recommend a big TV as your monitor, it simply too big and bright to sit close to for long period of time. Your best bet is keep the monitor for general pc work and buy a TV for gaming if you have space