My mp3 impressions in general are as follows:
The only bitrate that fully delivers right midrange timbre is 320kb/s, no matter it is LAME, FhG or Blade. All other lose the "color" of sound a bit. Second closest is LAME 3.97 when you use --alt preset extreme.
All mp3 have a bit handicapped soundstage and source localization. It is hard to define the right placement of an instrument and its virtual distance from your ears. The worst is LAME with its Joint Stereo mode. Dual Channel and Force Joint Stereo aren't worth mentioning. Turning on Stereo helps but bitrate goes more for channel encoding, and therefore midrange loses warmth slightly. FhG, which you can try ripping your CDs with i.e. WMP11, gives the best bang for the buck IMHO. It encodes Joint Stereo but soundstage is wider and more stable, and SQ is satisfying. Instruments are better articulated than with LAME as well. The last is Blade which is CBR and Stereo only. It has the best stage and sound clarity but it sound boring and fatigued sometimes. Interesting thing is that I ABX'ed myself using foobar2000 and a track in FLAC vs. mp3. When I was winning 4:0 with LAME 3.97 Preset Insane, I stopped the experiment and switched to Blade. Here I had real problems and decided I cannot exactly tell which is which.

So I assumed Blade 320kb/s is "transparent" for me. After longer listening you can realize its boredom and lack of dynamics, but not in quick comparison tests. The setup was: HP Compaq laptop and Senns HD 595 / CX300.
Last word goes for FhG. IMHO this codec gives the best tradeoff between soundstage, dynamics and tonal balance. I haven't tried ABX tests between FhG and lossless so far but find this codec superior to others. No surprise to remind that Fraunhofer (hence FhG) invented mp3 format.
