The advantage of Jeffs is easier to use, is quick to use mutiple layers one after another, I can do 3 or 4 in the same time as one EGP layer. Plus no need to wait 12-24 hours between layers either. Looks slightly better too. I have not been able to test if it is durable enough yet, EGP has a proven long lasting nature, but I fear Jeffs AGT's ease of use must sacrifice something.
The 50/50 is very good mainly down to its price and almost Pinnacle Souveran looks for lot's less money, Is easy on and off, and said to be durable. Of late I have been spolit with some other products so am not as taken by it as I was origionally. But for the price range it is in, it is a no brainer not to choose it. P21s though it lacks durability I still love the way it looks on Silver and Blues.