Another thumbs-up for Maxwell Screen
Today I received and installed a second-hand, but mint, Maxwell HI-LUX Brilliant Matte 4.7 Focus screen in my Linhof Technika V (4x5in). The conversion was easy (took 5 minutes), no need to mess with shims etc. Before this, I used Steve Hopf's wonderful fine ground glass. Of course, this requires a good dark cloth, even with a 150mm lens (I can only imagine how difficult < 90mm must be).
I am blown away by how good this screen is. Though I do not have any wide-angle lenses (I shoot primarily 150mm, 360mm, 500mm) it is an unbelievable experience to be able to focus clearly into the corners, without a dark cloth. This actually beats my Mamiya RB67 focusing screen for brightness and accuracy, which is not an easy feat.
What a piece of optical engineering... I am not sure that I would pay the (steep) new price, and I think it's very poor of Bill Maxwell not to make his products more accessible by offering, for example, online ordering (common complaint on the forums) but the screen is simply superb.
The enjoyment factor of using a large format camera literally doubles when you can clearly see what's going on, and focus even in very dim light, etc.
I cannot recommend this strongly enough.