I didn't know about color space before I went on my honeymoon and shot using srgb on my canon rebel t3i. If I change it to rgb, will I gain quality as if I originally shot in rgb? I am using files for printing at my home, I have an epson pro 3880 which supports rgb.
You mean converting from sRGB to aRGB (Adobe RGB) ?
Then there is no advantage in converting. It's easy to convert, but you won't get back the 'out of range' colors Adobe RGB is able to capture.
Note that if you shoot in raw format, you can always use aRGB in the raw conversion stage, even if your camera is set to sRGB. If you have set your colour preference in the editor to 'always optimize for printing', the ACR module will send an aRGB version to the editor.