As someone who DIYs boards and also purchased, received and rode a Backfire Ranger X1 I can tell you that it’s performance is actually “fine”. Not too exciting, but perfectly comfortable and rolls over most things I usually dodge.
The front wheels are indeed heavy but not enough to warrant changing. Keep in mind that this board has solid rubber tires and will not get punctured. If you change it, they would be lighter because it’s an air tube. My experience is that the solid rubber adds weight. But a lot of the weight is from the huge hub motors and 10s4p battery which is potted so you are essentially getting a few pounds of glue that makes the electronics water and vibration resistant.
For some reason, these hubs has a lot of resistance, it doesn’t free roll. If you have to lift and drag this board, pick it up by the back side so you get the resistance free front wheel and battery weight on the bottom.
As for the upgrade of ESC, I don’t see it as a problem as much as it used to be, the Chinese ESCs have gotten much better than they were a year ago, these are FOC silent and has smooth acceleration and brakes. Sure VESCs would be great but you really don’t want to push this board too hard since it’s using double kingpins, going faster would wobble your face into the street.