Nimbostratus
Cirrostratus
I've seen customers running configurations with hundreds of virtual servers and hundreds of pools. But I'd be leery of assuming configuration loads and load balancing would work efficiently with thousands of VS's and pools. You might try contacting an F5 presales engineer to get sizing suggestions and possibly do an evaluation with a similarly sized configuration.
Another thing to consider is whether you could combine some of the virtual servers and/or pools and still accomplish the same goal.
Aaron