Concerning the backlog (which I meant to write) I´m not actually sure if I get more things done with this new system but I feel better less stressed. I mostly use the priority-setting so far, as opposed to situation-based (all though I do mostly assign them tags as well so far). I just look at the top tag/tags and since they are prioritized I have a lot less task in them then if I were to see my whole list. - > less stress
I can select a notebook and a tag at the same time by selecting the notebook first and then pressing cmd and selecting a tag however, as far as I have seen, the fact that you have more than just the one tag selected doesnt show anywhere. Thats why I didnt notice it at first!