the short answer is yes....a dark hull can get really hot.  especially if left out in the sun.

i have one boat that is almost black and it gets noticably hotter than my lighter colored boats....it has the effect of softening the epoxy and i found it needed to be reskinned  after about 8 years of use.....faster wear than lighter colored boats.   i live in the mid-atlantic area.....so summers can get reasonably hot.   florida would be worse.....so in general i have been avoiding black or very dark for anyting that might be laying in the sun for a long time.

other than heat, dark is also hard to see on the water and is not a color i would generally go with if i am routinely mixing it up with motor boats or larger boat traffic.  being seen to me is important.

yellow is the most visible of the colors you mentioned and can look really nice with a varnished deck.....

i have tried lots of colors....so you don't have to limit yourself to just one :)

I'm not disagreeing with anything Howard is saying, but I would like to point out that there are steps you can take to make living with a dark color easier if you want to. First, store it out of the sun. Next, get a light-colored cover for transport. Finally (and I believe that you're already doing this) leave the deck varnished or a light color. That way, when you're out paddling, the light deck will be reflecting the sunlight while the dark hull will be cooled by the water.

Depending on the brand of epoxy you're using, you can also prevent/postpone the weave telegraphing through by post-curing the epoxy. This needs to be done within a couple of days after it hardens. With System Three Silvertip, it's as easy as making a large bag for your boat from black plastic trash bags, sealing the boat inside and leaving it out in the sun for an afternoon. You want it to get up to well over 100 degrees F. This raises the heat deflection and service temperatures which delays the heat softening. I don't know if this is possible with MAS, check with the manufacturer.

And wear an orange vest.

Laszlo