What did you decide?
Just joined the forum and saw your dilemma. Was wondering what you decided to do. The reason I ask (this is gonna sound obnoxious) is that I actually have both. I have the M3 CP (2012) and my fiancÚ has the Spyder. We've tracked both and, in my opinion, if its a weekend thing, get the Spyder. There's something real special about it. It's uncompromising which I love. And, to be honest with you, the top is easy to put on/take off once you've done it a few times. Not sure where you live but if it doesn't rain much, it's really not a big issue. Anyway, good luck and you can't go wrong either way.
PS- personally, if I could go back in time I'd get the Cayman R first.