I have been driving mine with 944 arms and coilover, with single shear bolt on the bottom for several thousand miles now. mostly track drag and autocross.
No problems at all!
The 14mm bolt is probably the strongest on the whole car! its a 14-9 bolt, that is it wil hold 140kg pr square mm! that will give you a couple of tonn's to spare even if you take all the weight on one wheel.
I have no worries using it like this.
the pic's show what happen if you try to drill holes in the brakedrum to make it lighter...
and even if the bolt should break-your car wil only be lowered a bit.