As people who have sung with and under me probably know, I'm not a fan of the overuse of psalm tones. Chanting psalms in the office? Great use for them. Singing the gloria patri during the introit? Fantastic. Psalm verses during communion? Wonderful. But replacing a gradual? Please no! Psalm tones are great for supporting psalm verses, but not for primary melodies. It is always such a shame to hear propers reduced to psalm tones, especially in the ordinary form where the graduale simplex could be used, or even many english propers.
Don't get me wrong, it is better to hear propers sung than not.
If you're struggling to put together a gradual with your choir, you should check out the Chants Abrégés! I don't currently direct a schola, but last year when I was getting one off the ground, we used it frequently to pull together the gradual, when we weren't quite ready to pull off the full versions in a reasonable amount of time. As we grew in skill, we moved beyond it, and only used it occasionally when we were faced with more difficult chants and limited time. It also has simplified alleluias as well, though the verses are set to psalm tones.
Now I do have to give you fair warning, other than the music itself, the book is entirely in french. I have found the easiest way to find a chant is to know the name of the chant you want and use the index to find a page number instead of trying to decipher the french headings. Still usable, just one extra step.
Thanks to the CMAA, this book is now back in print! If you are in a schola who has trouble with graduals, check this book out!