Now, in order to save battery when using 3G I manually disable HSPA in the Service Mode menu. This forces the phone to connect only to 3G, which is slower than HSPA (but noticeably faster than 2G) and drains far less battery. This menu is accessed by entering *#*#301279#*#* in the dialer. I've managed to do this in CyanogenMod 10 and 11, and in CyanAOSP, but not with GamerzRom. I haven't been lucky in getting the developer to reply to this question, which is why I'm posting it here.
From what little I could find, it seems like the developer deleted the service mode because it was a RAM hog, but I was wondering if there was another way to access it or disable HSPA (but not 3G) in another way.