I wouldn't mount anything to your benches. I built 3 tables and originally thought I would mount my grinder, sander, band saw and drill press to one, creating a movable "machining area." However, what I've determined, over the course of my build so far, is that it's far better to be able to move things around and set them up as needed. People that incorporate dimplers, back-riveting plates and other things into their tables quickly find that there is some compromise that's made because of how they mount those items. Keep things movable, is my advice.
Now, that doesn't mean you shouldn't think about how you're going to clamp things in place in order to use them. For instance, my DRDT2 dimpler clamps beautifully across my table, with a clamp on each side. I have a mat that I use with the back-riveting plate that's just the right thickness, so the material slides right across the plate. I have cross clamps that I use to secure items vertically across my tables. Also, my tables are able to be used in conjunction with each other (i.e. they can be set up side to side, or lengthwise with each other to turn into larger work surfaces.)