This is such a broad and general topic that it's hard to give just one answer but in very general terms, with a touring bike the riding position is more relaxed than a bike configured for racing. Sitting straight up on a racing saddle might not be what most people find comfortable while a B17 is more suitable. If your racing saddle is comfortable for you then ride it but to the average touring rider, it's hard to keep that ass over head riding position for days on end.