I am all for getting rid of the pool free-loaders! However, I'm not particularly thrilled with any of the options suggested. I've been to Vero and the automatic gate was a pain. I forgot my room key more than once at my pool chair and had to "piggy-back" on someone to get back to my family. I don't like the idea of having a CM randomly checking room keys because I really don't want to be bothered once I've settled in. Also, random key checks has more of a "guilty until proven innocent" feel to it for me.
Of all the options, I like the wristband one the best. I don't think that every pool needs a wristband, just the premier pools where a lot of the abuse is like at SAB, BW, Poly, AKL & WL. And then, maybe only at the busy times ... you really don't need someone handing out wristbands at 8:00 pm. The color could change daily (or weekly) and the design would be different for each hotel. You can either get your wristband when you get your towel, or a CM could check everyone's room key and give you a wristband when you're OK'd. I'm still not particularly happy with wearing a wristband, but I think it would free up more space at the pools with fewer freeloaders and I wouldn't be looking over my shoulder when I pool hop.
I think that some people will be able to get around any kind of "security" method. However, the majority of the freeloaders will be deterred and more room will open up for the rest of us.