Maximum number of block erupters raspberry pi can handle? I'm trying to figure out where the bottle neck in terms of bandwidth would be.

Assume:


no other processes running on raspberry pi (700MHz processor, no
overclocking)
no limit on internet up/down rates no limit on power of
external USB hub (5V, 12A power supply)


What is the maximum data rate that the usb bus can handle?
What is the maximum data rate a block erupter could ever need (I don't know how to convert Hashes/s to Bytes/s on the USB bus)

Are there tools I can use to grab these numbers (e.g. some utility like netcat?)

Can I put a 10-port usb hub in each of the two raspberry pi usb ports?
You can probably go up to the maximum of 127 devices if you really wanted (the USB2 limit), remembering though that the Ethernet adaptor is one, and each hub also counts in one. Word on the street also indicates a 49 Eruptor limit, though that's probably just a software limitation. 

The transfer speed will never be an issue. 

The CPU speed will never be an issue.