I've tried electric combat. I "electrified" a Li'l Hacker using a 25-12 motor, an inexpensive motor control, a 3 cell 1000mAh battery, a cheapie car radio for motor control.
It flew just fine. It could easily do loops and figure 8's.(meant to include this) It can easily fly combat against a similar plane. Flyers can learn to fly upside down, do loops, wingovers, and how to align for a cut.
The problems is scaling up. I see are several. It is significantly heavier and less powerful than a Black Widow fire wall mounted engine. But the electric version is plenty to learn the basics of flying C/L combat. It all depends on timing, learning to feel the plane, learning to fly next to another flyer.
If you want a low cost, flyable training method try "pole" flying using a clay weight to balance the plane, and20-25 ft. lines running through the brackets on an 8-10ft pole. All three of my kids learned to fly noiselessly(except for the shouting) in the backyard. After that they all easily learned to fly an engine powered plane and tried contest flying. Emily learned to sucker guys into the ground. Alan learned to fly Fast combat and won the open at the NATS the summer he graduated from high school with female guile. Steph kinda said "ehnnn! She preferred running the concession stand.