Today I received the Losi 10250Kv motor and the ESC.
I set up a test with my blue arrow receiver at 5V and this set up works fine at 5V. It will be interesting to see if it also works at 3,7V. There has been reports of problems with the ESCs at 3,7V but they seem rare.
I am still missing the PWM to PPM converter so I can't complete the upgrade yet.