I was just playing through my song on Medium drums and discovered that with drum fills on it's a lot harder than I expected.
The song is at 188 bpm and something like half of the measures anticipate the measure change - the effective downbeat is an eighth-note early.
Most of the right-hand timekeeping is on quarter notes although there are stretches where it's in eighths (on Expert only). During those 50% of measures above, no kick ever falls on the '1' of the measure; one always falls on the prior eighth. (The hat/ride almost always still fall on the 1.)
So what this means is you end up with a lot of steady right-hand timekeeping on 1,2,3,4 along with a kick on 4-and (and elsewhere). Fortunately there's few crashes without prior fills; when there are, playing them on the RB kit with the hat on yellow is awkward, since you have to play 4:yellow, 4-and:green, 1:yellow, which is "rough" at 188 bpm. (Or would be at lower difficulties.)
Ok, so, that's the set up: it's a little cruel if I were to make people doing quarter-note timekeeping play 4:yellow, 4-and:green, 1:yellow when you're at 188 bpm. Obviously on the difficulty levels where that's inappropriate I can thin out the hats to make it easier.
The problem is drum fills on the lower difficulties. These fills end up in places where there's no crash in the original, and there's steady quarter-note timekeeping. For the higher difficulty levels to feel right with the anticipation, the fill has to end on 4-and. That means when you do a drum fill on Medium, you end up having to hit a crash on 4-and, and then immediately jump back to quarter-note timekeeping on the 1. (In these cases there's never a kick on the 1, so it's not infeasible, it just doesn't feel appropriate for the difficulty setting, and it doesn't feel fun: it feels like the game is screwing with you when you choose to do a fill. The most plausible outcome if I leave it this way is a Medium player would have to learn to hit the green on 4-and with the right hand, and then the yellow on 1 with the left hand, and then move the left hand over to red and the right hand to 2. That's learnable, but aren't fills supposed to be fun? Having to work this hard on how you "recover" from them seems like the entirely wrong feel.)
The only thing I can see to do is to get rid of the hat on 1 of the measure following a drum fill for the Medium track. But now I'm breaking down the steady timekeeping of Medium when you're not playing drum fills; every time you get to one of these spots where there would have been a drum fill if you had the overdrive, you get silence on 1, and you're going to not feel connected to the music (I assume).
Bottom line, the ideal solution would either be for me to be able to adjust the fill lane timing to be different in Medium (which doesn't seem possible--I assume the 5 drum fill lanes are for the five pads, not for, uh, 5 difficulty levels), or for there to be a way to say 'remove these gems if-and-only-if there was a drum fill', which also doesn't exist as far as I know. So I'm stuck for a satisfactory solution.
(I haven't checked Easy with drum fills yet but it probably has the same problem.)
Am I missing something? Or is there a different approach? Or do I just have to live with one of my awkward solutions?