Most parts of the country have been in drought conditions this year, and everyone is having either QOC issues, blowout issues, or both since the grass is so dry and limp. Before selling your mower you should try a set of lower lift blades. They create less of a dust storm, and in many cases they improve the QOC due to less turbulence under the deck in thinner grasses. I did on my Z950, and it made a huge difference in blowout and my QOC did improve.
As for which deck is best, that's gonna net you a lot of opinionated answers. Everyone likes to defend the choice they made. I bought a 7 Iron (actually had a few now) because I knew how well they cut and discharge in any condition, so it was an easy choice for me. The Velocity + took first place last year here in a "best deck under all conditions" poll. Many here are reporting excellent results with their X factor decks, but a few have had a little trouble getting the cut they are needing. I was supposed to demo a gravely Pro-stance with the X factor deck today, but there was a snafu in the communications somehow, so it'll have to be next week sometime now.