there is more involved than just having an extra nipple, the number you found, 210-800-30-48 even though it has a 210 prefix is only applicable to the 208 CLK models which are coupes, and yours being a wagon.
i would say there are definately items related to the central locking and other systems that will not work properly or even at all. the pump requires version coding depending on the vehicle type and other parameters, i would say save your money and try to fing the correct pump. and when i look up the number in my mercedes Parts program it specifically says that the new part must be coded using the hand held tester.
there are a few older numbers that are compatible with this car, for one reason or another mercedes replaced them with updated units, the previous pumps with the old numbers may have had issues and were replace, here are the numbers, but i recommend that you call mercedes and see what the most current number is, even the one that is in the car may have already been updated.
210-800-13-48
replaced by
210-800-21-48
replaced by
210-800-29-48
hope this helps, and if your local dealer will not give you the current number let me know, i will call mine and get it for you.