We did 4 in 4th grade and that was a mistake. I loved it, but it was definitely too advanced and my dd kept telling me how hard it was, but I made her do it anyway. I should have listened to her and gone down to 3 that year.
Also, I am assuming that 6 is not scheduled in the manual, or is it? If not, how fast should we move through the book, and do we do the writing assignments in the book, or do we just use the Writing with the best or another writing curriculum of our choice? Hope this makes sense, I haven't had my tea yet this morning!

MIssy OH, if you read this thread, thanks for asking great questions, they were just what I was wanting to know too!

TIA,
Shelly