A Buddy Key?

[Ouch!]

Likely, but not a good judge by any measure. Your best bet of finding out whether or not you'll like FFXIV is by looking up information regarding FFXIV. A good place to start, if you're not willing to look far, is the FFXIV here, which has a thread dedicated to information coming out of the beta.

The combat system has been completely reworked for FFXIV and bears little resemblance to FFXI. About the only constant I've been able to see so far is that you can change your class at will; however, the manner and function of this is entirely different than it is in FFXI. The parallels for game play, as it seems, end there. Also, FFXI is almost entirely party-based which FFXIV allows freedom for soloing. In many ways, I imagine FFXI will give you a very many wrong ideas about FFXIV.

I would not recommend even starting FFXI now regardless of motivations. The recent level increase has all but vacated low-level zones. Starting from scratch at this point would be infuriating. That said, if Square Enix has stopped giving out buddy keys, I doubt you'll find one, and a two week trial is hardly enough to even experience half of what you need to in order to properly judge FFXI.