all 4 bars triangulated

I believe that a satchell link has the upper bars triangulated in one direction and the lower bars triangulated in the opposite direction. What you are talking about is just an upside down wishbone 4-link.

A Satchell link is when the upper bars are parallel (some minor angle can be used to dial in a desireable amount of roll-steer) and the lower bars are triangulated so that the bars are wide on the rearend and close on the chassis.

By lowering the roll-center it increases the weight transfer when cornering and increases traction. It is not needed on a mini, it was originally brought up as an option for when space is tight.

so why does bag over bar stress the bag more, i want to run this set up on my fullsize c1500 cause most people have said better ride quality and lift than bag over axle

It doesn't "stress" the bag any more than a bag over axle set up. The bag will take more pressure to lift the vehicle, but that is what the double convoluted bags are designed for. Don't worry about stressing the bag, as long as the pressure is below 150psi you should be fine.

thanks!!