Personally i think 4GB is overrated. Seen enough benchmarks to prove it. I run SLI with 3 Screens and can run just about anything with smooth framerates.
Oh yeah forgot to mention 1920x1080p is my max resolution. I have no intention of going multi-monitor in the future. But wow, you're running at 5760x1080. What are your FPS like? 40-60? Higher? Lower?