If the mids are boosted, it's not neutral either. Many refer to that signature as sweet. If the mids and bass are boosted, then we get warm and/or warm and sweet. That isn't neutral either. If mids and treble are boosted, it's bright. If only treble is boosted, it's called treble-happy None of the above are truly neutral.
The UE 900 is closer to neutral than the TF10 (based on what I've read, descriptions, etc.). The UE 900 is still not neutral.