I've owned and used them both. I could hear no difference in sound between them and would expect none, except at the very, very bottom of the frequency range where the built in high-pass filtering in the amplifiers have different slopes. For that matter you can include the TLM 193, which is built around the same capsule--it sounds just like the cardioid setting of the TLM 170 or U 89 except that it has even less filtering at the bottom end in the amplifier.
All are very good microphones, but not very popular outside the classical world because they lack the usual "Neumann signature sound" (they don't emphasize the midrange or the high end to speak of). People who are into the "vintage Neumann" sound generally dislike this series. They're not "vocal microphones" in the sense of making a voice sound bigger or more impressive or professional than it really is, like a U 47 does. They are reliable, more or less neutral-sounding microphones. Again the frequency response in the upper midrange isn't quite as smooth as the (smoothed, idealized) printed graphs indicate, but the overall shape of the curves is about right.
Internal shock mounting in a microphone is an emergency measure, not magic--it can make an otherwise unusable recording usable, but you can still hear the effects of ordinary bumps and vibrations.
Let me know if you have any other questions about these.
--best regards