@Glaucus
So I think we're talking about something slightly different then what tar does.
We are not. The only difference is that 'LZX' does the merging inside the program itself, whereas UNIX tar doesn't itself compress the stream, but leaves it to external program.
The only advantage of the LZX method is that the program "knows" how to skip data when it want to decompress single file somewhere in the middle of the stream. Tar + external archiving app doesn't know this, and the whole tar file needs to be decompressed until the specific file is encountered.
tar + external app is great because it's flexible. Once better archiving applications arrive the archiver can be easily replaced (for example tar + gz vs tar + bzip2). LZX is forever tied to the compression algorithm it has built-in.
