ABR in LAME seems to be screwed up now (very poor audio quality), and LAME is still defaulting to Stereo instead of Joint Stereo, but at least now you have a choice... before, it forced you to old-style Stereo. But if you're gonna fix it, at least do it (right). Full discussion of this is here:
Unless you want to learn a lot about Channel Modes, skip down to the bottom to see the update now that v2.24 has been released.
If you plan on encoding with LAME, I would strongly suggest upgrading to 2.24, manually switching to Joint Stereo, and avoiding the use of ABR for now (unless you don't get a bad result). Most people use VBR or CBR anyway, but I happened to be encoding to ABR as my first test. At first I thought it was my new drive causing the problem!
The difference between Joint Stereo (better) and Stereo (not better) is an extremely significant one, especially at medium to low bitrates, so considering Joint Stereo (officially the default for LAME) is not available AT ALL IN ANY INCARNATION OF PLEXTOOLS up until this v2.24, yes, it's worth it to upgrade if you plan on encoding.