Quote Originally Posted by Niwashi View Post
It might depend on just how much of the level 50 stuff you want to do. Besides the MSQ, which you need to do, there is a ton of optional level 50 content as well.

I'm holding off on registering my copy of HW because I want to do all of it. While doing just the necessary parts with the higher level cap might give you a nice boost of an extra couple levels or so, I'm afraid that doing everything could take me all the way to 60 before even starting the HW content and that could be enough to spoil it.

Most people, however, prefer to unlock the expansion and get the advantage of a bit of extra leveling along the way. It means less grinding once reaching Ishgard that way.
Unlikely to take you all the way to 60 unless you really grind it. Personally I just managed to reach level 53 before entering Ishgard, and I did just about all of the extra quests - except the optional dungeons/trials.