Holding an HSPA connection on a GSM radio DOES consume noticably more battery over a slower connection like EDGE.

The same isn't true with CDMA - an idle EVDO connection doesn't consume a substantial amount of power over a 1xRTT connection. (yes it does consume more but it's hardly noticable)

In both cases, transferring data over the faster connection does take more power, but there's a power used vs time situation.

If you have push services enabled, or things that keep your data connection alive - keeping EVDO all of the time will be better for your battery - you may consume more power when it transmits but you're doing it over less time. On the opposite side, if your phone never uses data in standby, 1x will be better because it won't have to maintain the EVDO connection.

But the difference is VERY small. It's been a while since I have been able to test because I live in an area with no service now - so I only have 1x with my Airave.

Currently, overnight on 1x only I'll lose 3% battery (12% with Sprint Mobile email running all night - it was 35% with SEVEN!). With hybrid mode enabled, so it's searching for an EVDO connection all night - worse than having one - I'll only lose 6% battery (15% with push email). Sure, it may be twice the drain, but is that really the difference between 1 day and 3? I am inclined to say no.

But I'd love for it to come out so I eat my words haha