David:
Thanks for the compliment. With respect to your questions:
1) What are the respective playing abilities of the contributors?
I think Darius is the low handicapper among the four of us, but don't know how low he is. My handicap was 5 or 6 at its lowest and is now 10 or 11. Ran is about the same as me, might have been a little bit better at his best. Masa could break 80 when he was younger but I've got to give him shots now.
2) What tees do each of you generally play when visiting these courses?
I used to play the back tees the majority of the time [unless they were over 7000 yards], until about six or eight years ago. Now I mostly play the second set of tees. I think that's true for most of us.
3) How much do you think either of those bias you (if at all)?
I talked a bit about that in the introduction to the book ... what we like and why. Everyone's opinion has something to do with their own game. It is no more a "bias" to think about a course from the middle tees than to be a scratch player and judge it from the back. Personally, I am not a big fan of courses which have a set of really long back tees that none of their regular visitors can play, and I might knock the course down a half point for that if I'm trying to decide whether it is a 6 or a 7. [Other people might round up because of the same scenario, but probably none of the four of us would.] Ultimately, though, our opinion of a course is more a function of whether the holes are interesting, than whether they are testing for the scratch player.