OK, I have to disagree with Alans analysis of the EM6900s temp as he did it using a method that suits boiler and HX machines but is totally misleading for most thermoblock machines. The approach of punching out a double shots worth of water without any restriction is fine for a boiler or HX machine as the boiler (steam boiler for a HX) is a thermal reservoir that should supply water at the right temp for a volume far greater than that of a double espresso shot. The boiler acts as a very large thermal buffer between the heating elements and the water that enters and leaves the boiler or HX tube.
In a thermoblock machine, the thermoblock itself is the only thermal reservoir and has far, far less heat capacity than even a Gaggia sized boiler so it depends on the heating elements operating on the water passing through the passages to ensure that the correct temperature is reached by the time the water exits the thermoblock. Now assuming that the water in the tank is 25 deg C and the required temp at exit is 93 deg C (a 68 deg C temp increase), every ml of water will need 68 Calories of heat energy added => 285 joules. Now the unrestricted flow though the EM6900 will be in the order of 60ml in 10 seconds so for the correct water temp to be reached, the heating elements would be required to add about 17 kilojoules of heat which corresponds to 1700W of heating power if there are no losses (ha!). Now the EM6900 has a 1000W heating element for each of its thermoblocks so it cannot keep up with the energy demand for unrestricted flow so the water flowing into the cup drops off in temp asymtopically towards the steady state unrestricted flow temp - about 64 deg C
BUT if the flow is restricted to proper extraction times (60ml in 25 sec) the average heating power required drops to about 680W so the thermoblock has more than enough heating power to reach the required output temp and will cycle the heating elements on and off to keep the temperature in the proper range.
As long as the temperature control circuits in the EM6900 are up to scratch and calibrated properly, it should have no trouble delivering the required shot temperature for a properly ground, dosed and tamped shot (it should work fine down to about a 19 second double shot - allowing for a bit of heat loss). In fact if it was sufficiently sophisticated, shot temperature control could be better than any traditional machine.