No, I have 7-10 mA usage with 3g. However it really depends on location and radio conditions. Having the power usage that high means that your phone might be constantly searching for better 3g APs for your location, or constantly switching between two or more APs. When boosting for better signal and for locating surrounding APs the 3g radio can use 100-150 mA.

Note that more APs in the surrounding area may cause more problems than having only one.

It may also help to switch 3g only in case that your phone is constantly on the verge of switching to 2g and keeping the radio logic busy, although that probably ends up with disconnecting phone calls more easily.