John,
I have used the GF's EnduroVar. I'll take the Kem-Aqua over it every time... Don't get me wrong; GF's EnduroVar is a great product.
There is a special reducer for the Kem-Aqua that I use... you not supposed to thin it with water... I still have almost a gallon of the reducer you only use an oz. or so.
I have not found another product I like better than the Kem-Aqua Plus. It's amazing stuff.
Scott
Finishing is an 'Art & a Science'. Actually, it is a process. You must understand the properties and tendencies of the finish you are using. You must know the proper steps and techniques, then you must execute them properly.