Lots of good input from previous posters.
In terms of usage/selection, I have pairs of both and quite frankly no longer immediately go to the spike models. If I'm playingj/practising and need to be some where soon there after I'll wear the spikeless. I haven't seen much of a difference at all in stability; even in wet conditions. Go with a style that you like best.
That said, since you are paying top dollar for MyJoys and will likely have them for years, then you might want to go with the spiked version.