I have a similar setup with an Ariadne and get approx 200 kb/sec when doing transfers using SMBFS.
Using ariadne.device 1.44 with MiamiDX.
Have you tried using FTP instead to test the hardware and drivers properly? FTP is faster as it doesn't have as many protocol overheads.
Also check you have the latest SMBFS, which is ver 1.63.
And also try SMBFS connecting to an Amiga running Samba, or a different PC.
