Epoxy for finishing???
To my thinking there are two uses for epoxy: to fill voids and to coat the inside of a hollow-form. The thought of using it as an exterior finish is, again to my thinking, bizarre. From all I've read, spraying it is next to impossible - that leaves wiping and brushing. Sanding a fill spot is one thing - sanding epoxy brush-marks quite another. While there are a few that can "torch it flat", not me.
Here's another something to think about: after the first coat of "whatever", you're no longer in the wood finishing business - you're in the finish finishing business. The surface of the finish is the issue. If the finish is low-solids and penetrates, then the surface of the wood becomes the surface of the finish, with all its grain patterns and anomolies. As most "low-solids finish" never really set, the next coat blends in. However, with epoxy, after one coat, you're in the epoxy finishing business. All subsequent coatings will have to bond mechanically. If that coat of epoxy is less than perfect, each following coat will be no better and probably worse.
I have used WEST and System-3. Dave Schweitzer of D-Way Tools turned me on to Aero-Marine, specifically the 300-series low viscosity. It actually penetrates and, when mixed with colloidal silica or other thickeners, does whatever fill-job you might come across. As our Grand Pooh-Bah stated, a jewelers scale with graduation of .1-gram is a most valued tool in any shop. The Aero-Marine, just like the System-3, is 100/44. If you want maybe 1/4" in a mouthwash cup, that's 5-part resin and 2.2-hardner. I'll stir any colorant into the resin, stir, and then add the hardner - after that comes the thickener. I've found that you can actually shoot the 300-series in a #22 hypodermic (buy from a feedstore - it's much cheaper). Cracks that most would fill with CA are filled with epoxy - while I haven't done proper testing, I believe epoxy to be a superior long-term fix.
Epoxy is an integral element to all my "secondary" turning (after the vessel is around 6%MC). I inject it under the bark inclusions, fill little cracks, thicken and fill large cracks, and coat the inside. But you gotta have a scale - I bought a Sartorius AY511 M-prove scale from Itin Scales for $136 - it measures each drop.
The above is just my opinion - I could be wrong. And to those guys that do great finishes with epoxy, hats off.
John