The specification you're requesting don't really exist as true benchmarks,
as there are too many variables inherent in any data transmission. Most
communication hardware specifications cite baud rates and bps ratings, and
use that as the basis of comparison with other products.
The AppleFax Modem is an often misunderstood product. It is a Group
3-compatible facsimile device, and communicates with other AppleFax Modems
at 9600bps in a modem-like fashion. It's important to note the latter
point, as many users mistakenly believe that it also functions as a
standard modem.
As far as fax transmission goes, the Group 3 protocols call for extensive
error checking, which slows data throughput. In addition, Group 3 fax
machines automatically lower their transmission rates based on the
noisiness of the phone line. These two factors often make the fax modem
appear to be transmitting slower than it actually is.