Is it ok to keep the roof open

[Frodo]

Originally Posted by elgyqc

For me the scariest thing would be an unexpected rainstorm that would flood and ruin the immobilizer...

Not that big a deal. Really.
You run into a sudden rainstorm in the Boxsta, gun it. Really. The airflow shoots the water harmlessly right on out the back. (Actually? Not totally true. You do get a few drops that run up the windshield and drip from the corners into the car...but it's minor.)

That said, I do in those circumstances generally try to get the top up if I can. Do the mod that allows you to do that without having to totally bring the car to a stop...comes in handy. Run the AC for a few minutes and the little bit of moisture you took on is gone...