I HAVE 1.8 ON MY MINECRAFT AND IT WORKS FINE!!!!
I have to check with the server though, to see if I can still connect to that (Might be an issue with the sever still bein 1.7.3 if it is still that.)
I think you guys shoudl be able to use 1.8, if I can without a paid account! My only issue is the shadows keep glitching for me.