I'll just be the voice of doom and gloom and remind you that the 5D has lukewarm focusing and metering compared to the equivalently priced Nikon D300 APS-sensor camera. You get what you pay for, and with a Nikon you get a professional build quality versus a prosumer camera. Given that the D300 finder is pretty darn good for its size, I consider it a viable option to a 5D. But that's just a skeptical partisan talking ;-)
For that matter, I found the Pany G1 EVF to be as nice or better than the Full-Frame finders I've tried. Image quality is pretty good and they sell for peanuts.