Well, by knowing which building the german player gets you can adapt way better than how he can do with you. If I don't see an early upgrade to T2 I would think my opponent wants to go heavy T1 into T3/call-in and I would just react by going T1 (snipers) into T4 (SU-85s).
Allowing you to know which buildings are being teched and built would still be useful, but certainly not as useful as knowing which units are produced or when mines are placed (that in the hands of a good player would mean being able to constantly prepare counters to everything).
Radio intercept is also a 0CP ability so it's something you unlock very early in the game and that lasts for the whole game so I can see why people are concerned about its balance.
I am not saying I agree or disagree with it over performing because I don't think I have tested it enough to make bold statements on its balance (this applies also to PPSh). That being said, I also doubt anyone here has tested it enough to make so strong judgements on either sides.
But feel free to continue your discussion, I just gave my 2cents
If I would be the one called to balance it I would at least remove the notifications about mines being placed.