SL63 Pre vs Post Facelift?

[M@r]{]

Hey all. I've wanted an SL Merc for some time but never been in a positive where one would fit my needs, well I've found myself in the lucky position of looking for a daily drive and something a little special. The SL63 is on the top of my list. First question, Is it worth stretching the budget to a facelift? 2016 onwards? I've noticed the pre-facelift 2014/15 cars have the performance pack as standard? So I've narrowed my search to a 2014/15 Pre or a facelift.

I'm after opinions on the pro's and con's. A facelift is going to cost me an extra £20k, is it worth it? What are the benefits? And any downsides, such as greater depreciation? And any other hints and tips on buying one of these cars would also be really appreciated.

Thanks in advance.