I was out at the field with these two beauties yesterday doing some field testing with the Grayson SMJV2 motor and MA 6x4x3 prop combos that I bench tested and reported on in a previous article in this thread.
Conditions were fairly cool as I mention in the video, 8 C/46 F, so heat build up in the motor was not an issue and I don't believe would be an issue even in warmer summer months which is good as the SMJV2 motors normally run a bit hotter than other motors in general.
Compared to the other motors I have tested with this prop, the Turnigy D2826/6 2200 and the DYS BE2208/7 2600, speed wise it runs faster than the Turnigy 2200 and about the same as the DYS 2600 motor.
The SMJV2 is less efficient than both of these motors based on amp draw and how much "gas" it consumed from the battery, but it doesn't put a huge strain on a 40A ESC and 2200 3S 40C battery. If you were looking for a setup with the MA 6x4x3 prop that is peppier than your standard D2826/6 2200 motor and didn't already have a SMJV2 motor, I would go with the DYS 2600 motor, it is lighter and less expensive.
Even though the SMJV2 weighs 40 gr/1.4 oz more than the DYS 2600, it produces the same speed, at least according to my 55 yr old, MK1, eyeglass assisted eyes :) I suspect this is due to the larger "can" that it has a bit more "oomph" than the DYS 2600 motor which makes up for the extra weight.
If you already have a SMJV2, you won't notice any increase in speed compared to using a 6x4 APC prop, but you will find the setup runs cooler, draws less amps and is much quieter. As mentioned in the video, more of a high pitched sound similar to an EDF, but overall much quieter.
So I will continue to use these older motors for awhile, I'm happy with the performance and might as well squeeze some more flights out of them, these were the first park jet motors I ever purchased when I got into the hobby four years ago and still run strong. Besides, anything with "super mega" written on it has a bit higher "cool factor" I think :).