I put a temperature probe in the E61 grouphead to check the temp on the Mara X, and now i can coffidanlty say it does have stable temperature control. It reads a 1-2 Celsius higher in the E61 injection point, right about the shower, than what the manual says the temp ought to be in the various modes, so there might be some heat lose when the water hits the coffee. Several times I tried Mode 0 to potentially offset the high reading temperature, it doesn’t seem to be a good match for the medium roasts.