For PTT, anything over 1 second turns out to be a big deal in daily use. Don't underestimate the poorer user experience of the PTT from Verizon & ATT.

Besides the time thing, there is another important difference in that Nextel's PTT is a separate system that runs in parallel to the cellular voice service. That is why during major crises, Nextel PTT frequently works when other cellular systems, including VZ & ATT's PTT, become overwhelmed and shut down.

Google it and you'll find many postings about how Nextel PTT remained functioning after 9-11, Katrina, etc.

Also, Nextel phones have the off-network "Direct Talk" that no other company has.

NextMail is another wonderful PTT tool that is available only with Nextel.

So, there are other differentiating items that Nextel has