I believe this has been discussed before but I really think this may be useful for many set ups.
Split note: A second, alternate, midi note triggered at higher velocity. This potentially doubles the size of your kit. For single piezo, on the snare for example, the rim shot sample could be assigned. On a cymbal a bell sound could be assigned or a crash perhaps on a ride cymbal. The practical options are endless.
As discussed before this can be done in your VST but its not that straight forward. It means taking samples and moving zones and with a lot of library's there are scripts attached which get lost in the move.
I can't see this being a big issue from development but it will need some support here. So, if you think this may be of use to you please comment below.