Sorry I can't speak to the Guthrie theater research. I'm guessing that research was done more recently, so perhaps a second or third year student has more info.
Ditto with the class attendance. All I can speak to is my own experience, which is now not as relevant as what a second or third year can tell you since they tend to change things from year to year. Almost all of our classes were video taped and posted for us (audio with video showing the powerpoint that the instructor had up). However, that does not apply to the break out sessions and discussion groups, which were definitely mandatory attendance. As for lecture attendance, it was somewhat variable for my year. For some classes, the instructors didn't seem to mind if you skipped some lectures because you learned better on your own, whereas others would stress at the beginning of the block that they expected attendance everyday.
Regarding absences, if I ever had a doctor appointment or the like, I just submitted an electronic absence request and the dean's office approved it - never had to produce a note or anything. The only difficulty I ever ran into was with the Advanced Doctoring course, where you do actual clinical work or observation of real patients. But I feel it's understandable it might be difficult to reschedule alternate clinical opportunities at the last minute.
But really, I don't think any of that should be a concern in selecting a medical school. I would think that any medical school is going to help accommodate absences if you need to take them, and I'd certainly say that Mayo has done so for me. As for class attendance, perhaps a second or third year will chime in. I definitely learn better on my own for some topics, and sometimes it wasn't ideal that we were expected to attend class anyway. But generally the instructors were excellent and it was worthwhile. The times it wasn't, well, no place is perfect. I have no regrets at all about choosing to go to Mayo, but if your plan is to never go in to a class, and just watch taped lectures, Mayo probably isn't going to be your cup of tea and you'll be frustrated that you're expected to attend. I seem to recall a lot of small group discussion sessions with mandatory attendance during my second year. I almost always enjoyed those groups more than the lectures, so I didn't mind them, but I know there are definitely people who are not fans of small group sessions.
Also, as I said above, Mayo is pretty flexible about making changes each year. We evaluate every lecturer, block, session, etc., and if some aspect of a course is pervasively unpopular, they usually try to make a change for the following year. I recall hearing quite a few instructors (instructors = Mayo physicians) in charge of a block polling us to see what we thought of how time was divided between lectures and small groups, simulation experiences, whether we wanted to eliminate having quizzes (some blocks have them, some don't), etc. Which also tells you that someone who just finished their first year at Mayo may have had a very different experience than I did a few years ago....
For board preparation, it's hard to say. I do feel that there were some gaps in information that we had to study for on our own, but I'd guess there are going to be some gaps whenever a curriculum is systems based. Hard to say.... As for how we did, I actually don't know. Didn't go around asking how everyone did, nor did I ask what our class average was. Perhaps they released that info, but I think I was too wrapped up in my clinical rotations.
Sorry I'm not really able to give much helpful information here. It's funny, but I feel like my first and second year were ages ago. Class attendance seems so remote and meaningless, although I do remember a block or two where I wished the instructor had given us leave to study on our own instead. Anyway, the bottom line is that I think the clinical experiences and environment here can't be beat. I suppose it just depends on what's important to you.