The switch is between the old (1X) and new (EVDO) network. Depends on what you have available in your area.
iPhone's don't have that issue cuz they just don't know it. That's generally the mindset of Apple... mask stuff from the users and if they don't know it won't hurt them.
As for texting in 1X over EV, never heard that one.... I do know that 1X has the potential to draw more power in standby mode but it's not really a big deal. Flipping between 1X and EV is only an issue for some people doing data who'd rather it just stay put. Also if you're in an area with no EV coverage or excellent EV coverage it doesn't matter.. it's only when you're in a spotty EV area does this issue even remotely come up.
--Chris