For a Hasselblad MF camera, I'd only change the screen if I was really dissatisfied with it. I have stock screens in all of my MF cameras, and the only screen that's not stock is my Graflex Super Graphic.

I have a Brightscreen in my Graflex. The camera came with a replacement GG, which threw off the focus. I didn't initially realize that, and I bought a Brightscreen as a replacement. It required a little shimming (1 35mm strip, 1 LF strip) and it's absolutely great.

I was out photographing with another LF photographer, and he said that he had never seen a GG as bright as mine. It's a really excellent GG and Fresnel combination.

But I'd only upgrade a MF GG if you're really unhappy with what you have, not as something to blow some bucks on it. I'd buy more film first.