I have not stacked in a rather long time. I only do it when I use a microscope objective or at times the Canon MPE 64 lens mounted to the camera. The switch to 64 bit OS on my mac has rendered my programs useless. The objective is a 10:1 mounted on extension tubes when I need more magnification. I can almost get to the cellular level.
This is a shot of the reproductive organs of a viola flower. If memory serves there are 34 photos in this shot. I used a macro rail mounted to a work station I built.
My go to macro lens is a non IS Sigma 150mm. It handholds quite well with the twin head Canon flash. The above shots were taken with that rig handheld.
Shots of my macro setups.