I thought I saw somewhere the blackstone cover was not that great, and that they used a weber cover.
Blackstone is a very nice heavy duty weather "resistant" cover, however it is not "waterproof." Keep it sloped (tented, propped, jacked whatever the Fark you want to call it).
I guess I will find out soon as I just ordered one. I will go with the pan under the cover and see how that goes. Thanks