Off the top of my head I know that our 5.0 software (with a mOByDic) queries a non CAN based vehicle at about 18 times a second. I can't give you the CAN numbers off the top of my head, but it is much much faster.
The protocol does make a difference, the software makes a difference and the interface makes a difference.
We have tested against an ELM device, an ELM bluetooth device, various mOByDic devices and the BR-3 device, this question you posted has been needing a good answer for a long time. I promise to spend some time documenting some test results against various hardware/protocols and softwares available.
I have never tested the Mongoose, but I'd like to know the hardware limitations accross protocols for that as well.