thanks guys. i have to wait till i get mine to see if my layout works well. i think i will need to have 2 pads each tom to do rolls on the small pads, but i'm not sure. looks like its easier on the large pads on the ZX.
Couple of thoughts...
1) It will be interesting to see if you still like having the snare in between the OpenHH and Closed HH on the left edge of the ZD. I tried it yesterday for a spell, but when I wanted to play Open-Closed quickly, I found it uncomfortable to spread my digits across three buttons (unless I brought the left thumb into the equation-awkward). I went back to: OpenHH - ClosedHH - Snare; played by sliding the index and middle fingers up/down, as needed, occasionally ring finger on the snare. I like having the snare (outside edge) next to the tom bank because I often end up playing the toms immediately after a snare hit.
2) Unless you have extremely large fingers, you can absolutely do finger rolls on the smaller buttons, so you may find it unnecessary to duplicate the toms around the ZD. Even after a couple of days, I am finding that the biggest advantage in duplicating triggers is not so much for rolls, but to enable multiple combinations of sounds with either hand. For example, if I want to hit Crashx-Kick at the same time, it helps to have several ways to involve the hands to accomplish it. Also, duplicating certain heavily used triggers (kick, snare, hats, ride) enables ambidexterity (e.g. left or right lead).
3) I don't have any tom rims programmed. My V-Drum module is a TD-20, but my kit was upgraded from a V-Stage, so my toms are single trigger PD-80's. I haven't missed the rim sound on my V-Drums or the ZD. You can experiment both ways and see if you really need/want those extra triggers. If you sacrifice some/all tom rims, you could add a bunch of percussion sounds or other patches.
I made a few more adjustments to the design (see att'd) after another day of playing/practicing. Obviously, I am still experimenting with trigger placement to achieve optimum efficiency of movement (for me). I have started woodshedding with drumset 101 materials (e.g. Chaffee, Chapin) because learning to play patterns on the ZD, with more than two digits at a time, uses entirely different brain synapses. Fortunately, progress is coming pretty rapidly... I haven't even started to play jazz patterns yet, which is on the exercise program for today. Maybe I'll change the layout again once I try playing along to my favorite Big Band jazz recordings. I guess that's why there are 16 presets in the ZD!