i agree that it will definitely sarcrifice your higher end bass but you don't lose SQ based on tuning...
personally I would only tune that low if you had a larger setup. 30hz will work just fine without sacrificing too much. that's what i use and I get plenty of lows no problem
put on is 28hz. just cause you tune to 30hz doesnt mean you cant hit 28.
the lowww note in bass i love you is like 4hz or some bullshit like that. tbh i would never play that song in my car as something that low, especially in a ported box, will just destroy your subs