I have the Dynon EFIS 10A and it has performed flawless. Wouldn't trade it for another brand.
You don't want to hear about my experience with MGL on their E-1 engine monitor. Oil pressure, oil temperature, EGT, CHT worked fine after many messages to MGL.
RPM indication, it would fluctuate 60 to 100 at best - won't put it on my lawn mower or my neighbor's garden tractor. At present the E-1 is in their shop.