Are you big or small? Those pieces get HEAVY when full. My hubby carries the keepall 55 with shoulder strap and he is 6'2 and can struggle when it is full. If you are a tidy packer the sirius would work for you, but I like the ablity to just chuck stuff in and zip it up (booze, hairdriers, that extra pair of shoes). I have the MC and can fill it and it's not too heavy and it fits on airplanes. Louis has like a 14 return policy, get your first pick and take it home to try, if you are not happy, exchange for the other. GOOD LVCK!