The bass/cello bit is something of a misnomer. The NS Omni bass used to be called the Bass/Cello but was renamed. These strings are bass guitar scale strings but have a rope core as oposed to the solid core on BG strings. That gives a slightly different tone to them. Never tried tuning in fifths so can't advise on that one. I find they give a much better tone, for my ears anyway, than the stock strings that come with the bass. They are certainly not floppy but have a comfortable tension. They are very expensive.