I used to shoot with two EOS 3 bodies and I don't recall them being too dim, but I have a 1N right now and it is acceptable. The VF is 100% coverage so it is a joy to look through, but it's not extremely bright. It's definitely usable, but I've seen brighter.

I have the EC-B split prism in mine which may or may not make the image darker, but it's just so darn handy because it is SUPER easy to tell when something is in focus. Especially if I am manually focusing.

I may try the original screen again, but I've been really happy with the EC-B.