I am 8 hours into my first 4g setup in a blade 18x20 2013 and I am impressed overall. I played 5 sets of doubles today and I had complete control over every shot. Comfort level was still good for a firm controlled poly. I still can't say the price is justified at roughly $17.00 a set.
I will be experimenting with the 4g as a cross with Pacific Classic Natural Gut in the mains on Wed, due to some positive feedback in this thread.
I really hate to cut the full 4g setup the way it is playing but my curiousity of a gut/poly setup in the blade is overwealming