both encoding modes can produce bad results if the settings do not correlate with the type of music you're trying to encode
the thing with abr is that a lot of people dont like it because it sets a specific bitrate target where the encoder does its best to keep it somewhere within that specified area. vbr with only -V doesn't. setting a maximum bitrate in vbr is obviously not recommended unless it -B 320 but u dont really need to put that in
stereo separation in mp3s depends on what stereo mode u choose and that basically has to do with the bitrate. it has nothing really to do with what encoding mode u choose, but rather what is the minimum bitrate. 192kbits and below should be encoded joint stereo. 224kbits and above should be encoded stereo. u could end up with significant artifacts if u encode stereo at too low bitrates, so for example if you're using vbr and the minimum bitrate there is 128kbits, then obviously you want to use joint stereo. joint stereo is a good technique to increase audio bandwidth at lower bitrates but it becomes kinda useless at higher bitrates. the price of joint stereo is obviously loss of stereo separation and some flange with live recordings or songs with a lot of wide stereo segments, but the good thing about it is that it increases encoding efficiency and it gives better results at lower bitrates then if you would have used true stereo instead. joint stereo with higher bitrates (i.e. 256 or 320kbits) can risk introducing artifacts too because at those bitrates you should encode stereo
remember whether you encode joint stereo or stereo in cbr mode, it doesn't affect file size in any way, only in vbr but even there the difference is not that big
hehe enjoy delerium.. :P sorry i couldn't upload the full length
its almost 12 minutes long and at 224kbits its almost 19mb
