For me, R1 & R2 were the easiest, but that's because I'm fairly familiar with individual tax. R3 was hard for me, and I'm definitely going to have to go over that again and again. R4 was medium. For some reason I really get partnership taxation, so that part of R4 was easy, but estates really confuse me, so that was hard. What was not easy, but in fact very annoying for me was the section about federal tax procedures and the legislative process. It wasn't hard because it's difficult, it's hard because it's very boring.
As far as R5-R8, I would say they are medium with spots of difficulty (for me, the whole signatures and negotiating instruments thing still is not straight in my mind). The law stuff is a ton of information, the homework questions are a lot wordier, which made me more tired when I was working them. Honestly, the NINJA notes are a lot more helpful to me with boiling down the law stuff than they are at boiling down the tax stuff. The last 4 lectures only make up about 20% of the exam, so I'm trying not to get bogged down in the law stuff during my final review.
REG- 53, 91
BEC- 88
FAR- 62, 85
AUD- 85
Ethics- 93