Pay the extra
Paying a little bit more for using their bikes will take a load of pressure off you doing the course on your bike. Just about everyone in my class dropped their bikes; one or two crashed their bikes hard. The cost to fix damage to your bike could easily be more than the extra fee. Like the Mastercard commercial, piece of mind, knowing that if you break it, it isn't coming out of your pocket, is priceless.
BTW: bikes have to be street legal, because they ride off the property on public roads - so mirrors, turn signals and the like are required - and the most likely bits to bust off in a drop.
Besides, no better way to test ride something different.
Chiang Mai, Thailand