Something must be done with x7s with no doubt. The question is - do we nerf them (if yeah - how), or do we introduce counters. I would prefer the latter. I must admit, i play defenders myself, but it started feeling dirty at some point. Defenders turn all the nice people to whiny, unhappy people. Token stack each turn at heavily undercosted ship (withx7) is just too much for most normal lists to handle. Especially against those z's or tie's trying to get their 1 hit, but it's impossible.
At some point just card pool is so big that options instead of getting better are just narrowing. The best builds and combos are just too great to take them down.
My prefered solution is just X-wing 2.0. It has to happen, and it better does as fast as possible. We need change, edition 2.0 can deal with token stacks with general, make titles built-in ships instead of autoinclude cards that you can forget, change turrets into mobile arcs, rebalance all the pilots and upgrades, maybe change some dials.
How i would make it happen? A big core-set like pack containing everything you need to transfer all the ships to 2.0 assuming that you have 1 of everything costing around, i dunno, 30$, and small transfer packs for around 3$ to transfer one of certain ship to 2.0 and reprint everything to make it 2.0. If it doesn't happen, the power creep will go on and the game will just fall apart. All the wargames and cardgames without rotation or ban system need it. Look at wh40k (from the good times). First few editions just fixed the mistakes of the previous one and changed the units. It made it fresh.\
You can even separate card packs from ships, making their price lower and preparing for 3.0.
Little trick i have found is play them yourself. You will then see theit weaknesses plain as day and know how to counter them better.