As someone who has two 2-4 screens and three 2-13 screens, I can attest that they are incredible focusing screens in terms of brightness and contrast. The view through them, when in focus, is every bit as clear and bright as one's own eyesight.
If one focuses very slowly in one direction, it can be initially tricky to get spot-on focus, as one can prematurely think that the image is in focus, as the view can look as clear and bright while still slightly out of focus as many focusing screens when they are in focus. But as you continue turning the focusing ring, the view becomes sharper and sharper. Thus, the best technique for focusing with these focusing screens is to use a quick back and forth focusing action. Using this technique, it is easy to get spot-on focus, even in pretty low light.
However, as great and as rare as the 2-series focusing screens are, $230 apiece is alot of money! I paid about $65 each for the first three, and paid about $85 and $95 each for the last two, which were bought within the last two years. Guess I should be happy with the rising prices, as I don't plan on buying any more of these screens and could make a bundle if I ever decide to sell any (although I have no plans to).