That leaves the Onyx RCR. I would argue that Onyx, and Stealth are both street bikes, that can make do in the dirt, but not nearly as well as a SurRon.
Onyx vs Stealth
60 claimed vs 55 mph
3000w vs 6200w, this is a little misleading. The Onyx can be easily programmed for more power, but it's motor is only rated for 70 amps.
1.65 kWh vs 2.5 kWh 72v battery
47" vs 45" wheelbase
33.38" vs 32.2" seat height
Single speed pedal drive vs manual 9 speed sequential pedal gear box. New Stealth's have a newer transmission with electric shifting.
Coil over twin shock vs Coil over mono shock
156 lb vs 120 lb my bike, new bombers are 140 lb
$5000 vs $12,800 list.
When I've ridden with an Onyx they seem pretty comparable performance wise when casual riding, which is not surprising considering they have similar motor power. I notice when an Onyx rides over rough ground a lot of them sound like rattle traps. You have to take measures to quiet down the rattles. Stealth's are very stealthy in comparison. Some might think that's a whinny complaint though. A more serious problem I have with them is the weight, and especially weight distribution. On one group ride I was talking with a Onyx owner, and he mentioned he thought his Onyx felt heavy. He invited me to pick it up off the stand. WOW, even though his bike had a stock "little" 23ah battery, just lifting it up off the side stand it felt like a ton of bricks to me. The optional 41ah battery must be unreal. Having a huge battery so high up in the frame makes the Onyx feel really top heavy. Both Stealth, and SurRon battery's are lower in the frame which lowers the bikes center of gravity a lot. When I ask him to try picking my bike up off the stand, we were both amazed that day.