With free shipping and easy water cleanup it sure could be tempting.
I would not choose it for my projects for a couple reasons..
First, what is it? With a water cleanup I'm thinking it's not an oil based marine spar varnish. I only put spar varnish on my hulls.
Second, it does not self level. With that fast cure time it could be a real pain to get a great finish with.
I'm sticking to the Epifanes...by the time I get to putting varnish on a hull the last thing I want to do is use an unfamiliar product. It dries fast enough for me (overnight) and the first thinned coats do a great job of penetrating. I don't mind doing some sanding to get to a nice finish.
If you use the Halcyon you should post your thoughts about it. The reviews at Jamestown were a bit mixed.