Although it’s been a long while since I’ve actually connected to the net with dial-up, I am currently tethering at reduced 2G speeds (voluntarily) although quasi-4G is available on my plan and my phone will do 3G. My workhorse Dell d410 tethers via wifi to the Android Optimus T (rooted, cyanogenmod).
I limit my mobile data to 2G for battery life and to remind me to be careful of my mobile bandwidth. Seems to the be polite thing to do. Counteract a few data hogs, maybe.
This isn’t my speedtest but it’s indicative of what Edge 2G looks like on TMO:
it’s 43kbps down (similar to dialup), 81kpbs up (about 2x dialup), with pings similar to dialup.