Well, sort-of. Are you transmitting megs of data?
2G higher peak current is a pain to supply (ie your power supply must be sized for it) but generally, the device isn't transmitting; even when it is transmitting, it'll be usually 1 or 2 slots up (never seen more be assigned), so that's an average current of 1/8 to 1/4 of the typical 1.55A, ie 193mA-387mA most likely. You add onto this the receive current, but that's less than half the transmit and if you're only sending kB of data, you'll almost never "see" the transmit current.
3G typical is 600-700mA at maximum power, continuously when a data connection is up. Yes, it'll be less than that at 0dBm, and you send data faster, but it's a big chunk of power that does not vary depending on how much you're sending. If you're sending megs, then sure this works out well, but it sucks for times you're not transmitting much data.
This is why 3G sucks for web browsing; lots of download, very little upload but you're still transmitting all the time. A serious step backwards from 2G TDMA.
That said, there's no substitute for actually measuring your use case, but if you're on 3G there's a big penalty for bringing a data connection up. Use it intensively when it's up.