Verizon's EV-DO is as spread as far and wide as AT&T's EDGE network. Both have the same handicaps (can't talk and surf at same time); and yet one is considered 2.75G and the other 3G when their theoretical speeds are very close to each other.
Theoretical is meaningless. Heck, EVDO Rev A's theoretical maximum is over 3MBps, but no one ever hits that.
EDGE does not go faster than ~384Kbps on any actual carrier or device, whereas in real life EVDO Rev A usually starts over 600Kbps and often hits 2Mbps, with a few getting 2.5Mbps.
Similarily, so-called 7.2 HSDPA will actually average 2.4Mbps in real life, according to studies where it's been used overseas, with speeds starting much lower and sometimes going much higher.