I do not understand your logic. First of all. You are connected to 2G AND you are using data link CONSTANTLY WITH APPS you are using.
Secondly for fairness it would be right to do comparison with same kind of setup. With two IM apps like gtalk and skype you are probably doubling your data rate with server and keeping N900 cpu & modem wake. Please before making this kind of statements try to even understand what is happening under the hood and try to make comparisons more scientifically.