I think the main issue between Sprint and Verizon's EV-DO service is that while Verion already has a steady Subscriber base for that service, Sprint does not; not to the level that Verizon has anyways.
What this results in is in VERY VERY STRICT usage rules on Verizon's network versus VERY VERY lax usage rules on Sprint Network. Basically, more than 5-10GB of usage month on Verizon's network and they will terminate your contract. That said, it is easy to see why.
In addition, all of Sprint's radio towers are appearantly 1900mhz, which allows for more EV-DO bandwidth per tower vs Verion's mixed 800mhz/1900mhz towers which, while supproting EV-DO, are geared for lower-bandwidth 800mhz service, and Verizon watches their QoS very carefully, hence the strict AUP. That said, in a conversation with a Phd in EE, I was told that was nonsense and that Verizon, like any other carrier, can't handle everyone d/l'ing to their hearts content without having it affect service quality. Basically, Sprint is being lax simply ebcause they don't want to alienate new customers, but once they form a nice and juicy EV-DO subscriber base, the hammer will come down.
Regardlesso fall of this, it has been proven through testing, on howard and evdo forums, that if you are in their respective ev-do zone, sprint will give you, albeit neglible, superior speeds.