The suggested low rates are 'way too much for precision IMAC stuff; especially if you set it up like the manual shows, with 1:1 ratios (i.e., servo horns as long as the control horns). This gives a tremendous amount of throw for 3D; but to do smooth aerobatics, you need to cut the throws so far back the servo is hardly moving. IOW, very little resolution/precision in the servo.

I eventually went to very small servo horns (the little circular ones that are "standard") and max ATVs.

Now, this assumes that you prefer to have full range of movement on your sticks when flying aerobatics. If you can get by with barely moving the stick, then the book set-up will do fine. I tried that, and there was no "repeatability". Sure, my lack of control, but nonetheless... So I went through the hassle of changing all my servo horns and found the sweet spot on the roll rate. I then adjusted my tx response to that and can now just ease the stick over to the stop and the airplane will roll at the desired rate.

There are several excellent threads on this forum regarding this exact topic. The time spent looking for them will be well spent once you find them. I learned a ton, plus there's a lot of good information on the IMAC site. Once you begin to delve into the subject of control geometry and its ramifications, you realize that you really didn't know ANYTHING about these critters; even after almost 20 years in the hobby.

I didn't approach this IMAC gig to compete; I began it to make myself a better pilot. If I never fly a contest, it will have served its purpose.