Christophern, Thanks for your reply. Can you explain why his advice is better? I'd really like to understand why I'm doing what I'm doing :)

Also, how much do I thin the paint? And with what?
Thanks!

I was told by a paint guy never to prime a foot traffic surface. It was something about primer not being designed for the type of twisty traction involved in shoes walking/scuffing around on flooring.
The newer floor paints are wonderously durable- I have an outdoor staircase and porch painted three years ago that still looks brand new, treads and all.

What he, she, said^
as to thinning, it will tell you on the can
I would go with the Ben Moore

Thank you both for taking the time to help me! Cearbhaill, what brand of paint did you use on your porch? I have to paint that too...
Thanks again!

I used Ben Moore Floor and Patio paint for my wood front porch floor in late summer. It hasn't been on long enough to evaluate it, but so far so good.

I would have preferred to use the alkyd version rather than this epoxy-reinforced latex, but it is not sold here. Interestingly, the can directions tell you to use primer, then the paint, and not to thin it. But the people in the Ben Moore store told me to simply thin the paint with water and use that as the primer, so that's what I did.

My porch paint is Sherwin Williams Porch and Floor Enamel.
Only because Benjamin Moore is too far away :) and the old timers at my very close SW store are extremely helpful.

been paint contracting for 33 years....I will take the old -timers anyday over a fresh-faced kid salesman at benny moore or sherwin.....YOU NEED TO ALWAYS USE AN OIL BASE PRIMER OUTSIDE. ...except for masonry......the oil base freezes the wood and makes it durable.......Yes, i like the v.o.c. laws, but there is no substitute for an oil- based primer.....for a deck I would use oil stain as a primer, not alkyd on walking areas. Its too soft......that old painter was right...good luck with your deck, and listen to us pro's and old timey painters, we've been there.