I am familiar with the GW product but not familiar with their exact formulation. Both their product and Cactus Juice are a methacylate blend. I just took at look at their technical specs and the biggest difference I see is they state a viscosity of 21.5 CPS while Cactus Juice is 5-10 CPS. Water is 1 CPS for comparison purposes so Cactus Juice will be thinner. Also, their cured hardness is 65d where Cactus Juice is 75d-85d. The higher the number, the harder the material.
I am sorry I did not reply sooner! I was sitting on a beach in The Dominican Republic when you originally posted and just got back Monday 12/16. On top of that, the day we left, I woke up with a bad sore throat and am now sick with some kind of sinus infection or the flu!