LENGTH (running time field), TLEN in ID3 ?? in FLAC, [TOS #6: moved from General Audio] Options

[HansBKK]

I have a bunch of MP3s, some have a TLEN file, some don't, haven't come across any problems so far.

Some intertubes references say this can be important for "proper seeking with VBRs" whatever that means.

Other places say don't worry about it.

The newer part of my collection is mostly FLAC, and that seems to have no issue, but if the value is important when converting to MP3, will FB2K handle this automagically or should I embed a "LENGTH" field say via MP3Tag?

And I realize this may be a heretical question here, but is there a free toolset (in either/both senses) better than FB2K on windoze for converting from FLAC to MP3, I'm trying to get all the tags over and am finding I have to change quite a few of MP3Tag's default mappings in order to get the ID3 tags converted properly (e.g. CONTENT GROUP rather than CONTENTGROUP). And of course the coverart would be nice.