www.kenyonracing.com is their web site. They are neat little race cars, spend most of their time on paved tracks. I understand they run a tight ship.
Mini sprints or lightning sprints stay on dirt tracks mostly. The big difference is the Kenyon's use a drive shaft and quick change rear end and the sprints use chain drive. I would guess cost is about the same for either class. We run MMSA mini sprints another group racing sprints is the AMSA.
When you get right down to it I guess it is what floats your boat.
I would suggest don't get in a big hurry go to the races where the different cars are racing, buy a pit pass and go down and talk to the racers at the track. There are very few of them that will bight your head off for talking to you about their passion and you will get a lot better insight into what you are getting into. You might also want to look at the TQ midgets. We are all related, we all like open wheel racing.
Have Fun
You can search IOW for Kenyon midget and or mini sprint and see what they are saying to one another. (see all of their dirty laundry)