I played against my brother over the weekend. He doesn't have much experience (I own the ships) and has only played once before, so I decided to try out a 3-ship y-wing build:
Gold Squadron Pilot
I felt that this gave me a couple different options when it came to play style, and it was kinda fun to pilot nothing but these old warhorses.
My brother fielded the following:
Obsidian Squadron Pilot
We used asteroids, but I don't think anyone ever took any damage from them. (Always lucky rolls) My brother charged full speed into the asteroids toward my squad. I was able to just get into range 3 on the first turn, and Horton (the highest skilled pilot on the board) earned his keep by torpedoing Mauler into space dust right off the bat.
Overall, his two advanced and two fighters were pretty well-matched with my three y-wings. He rolled well with his missile volleys and took out horton within three or four more turns.
Ion cannons were fun, but my brother played well enough not to get caught pointed right at any asteroids, and often I had to fire through one, giving his ties that fourth defense die. Eventually I was able to put enough distance between Dutch and Maarek to take him out with torpedoes.
The rounds proceeded pretty evenly after that, and eventually it came down to his tempest advanced with 1 hull remaining vs. my gold squadron y-wing with 2 hull. We jousted, but both missed. He k-turned while I attempted to flee back behind an asteroid, with my turret to protect the rear. He rolled a hit and a crit on his last attack, while my lonely green die came up blank. Only after we had everything put away did I remember the simultaneous attack rule. Tempest and Gold both are skill 2, so I should have gotten to fire back before being destroyed.
No matter. It was still a lot of fun to play two squads that were so evenly matched.
The all Y-Wing builds are interesting (I haven't tried one as I only have 1 Y-Wing). However, I just don't see how they can compete with the TIE swarm. Against an Imperial build that focuses on quality (which is what you faced) it seems as though many different builds would work. If you faced a swarm, there would be so many shots incoming and connecting against your 1 Agility Y-wings I can't imagine you'd last long.