The first couple of years it cost more though nowhere near 9% Andie. I benefitted by a year later by taking on an ex bank manager who understood far better than I did the terms and reduced things a lot. And then basically after a few years (apart from a bad 2008-09), we ran in credit virtually all the time.
It works, but you do have to be aware of why you are doing it, ie expansion or because you can’t actually make the job pay and need/want to delay the inevitable.
As I said, I haven’t had finance on a vehicle for 6 years because of that cheap facility.