Regarding hardware you really cannot ever have enough for maxwell, i think apple will launch a new pro soon. I am very happy with maxwell it's results are always predictable, i used artlantis for a few years when i had my slower power pc machine. This taught me the basics after i moved hard/software it was like running without ankle weights. Even if you get a super beast of a machine you will be tempted later to create a farm. Vray has speed on it's side i have seen some great images made with it, but with maxwell i think you get a lot more especially the full version. I am a bit biased as i've only used maxwell perhaps others will pitch in.
Your machine is no slouch it will render reasonably i'm sure, if not look at something like
http://www.felixrender.com/Personally i am a bit of a perfectionist when it comes to images, in my opinion it's the end result that matters not the time or quantity. Have you tried the free version ? It may give you a better understanding of the time involved with your system.
I have really enjoyed learning & using maxwell, there are some really helpful & inspirational guys here & the next limit forums. Also the plugin & studio gets regular updates and the devs frequent the forums this in my opinion makes a big diference.