I would like to know why RT do not offer 12 & 16 columns grid together with your designs. I mean, I know that one can change from 12 to 16, but I also understand that as Andy said
"it's not so trivial to change the grid system..."
.
So two things:
1) Give the option for 12 & 16 grid templates, as you do with the background level
2) Create 1 module position per column. This would give us much more control over the layout I think. With a 16 grid layout, where you can use each one of the 16 columns, you can control in a better way the dimensions of the blocks, since they are smaller.
I might be wrong here, but I think it should be possible and quite easy for you guys, since you already are experts on 960 grid system and Gantry.