Most all grommet machines function identically. Anvil on the bottom, die on the top, push them together deforming the grommet around the reeve. Hard to get a lot of variation here. The one area in which quality is a concern is the level of precision in machining the die. The grommet must slip on but there must be sufficient friction to hold it there and no more. Cheaper presses typically have cheaper dies.
As far as grommets in Coroplast, foamcore, or whatever, if the material is not thicker than the grommet is long plut a bit you can set it. I routinely set self-piercing grommets in 3mm aluminum laminate. No pre-drilling, just punch it right through with no more effort that setting a grommet in a banner.