The whole 0.6oz weight of cuben is a weird situation. According to Cubic tech you've got CT2K.08 at 0.74oz/yd2 and then the next lightest fabric is CT1K.08 at 0.51oz/yd. There really isn't a weight of cuben that weighs 0.6oz/yd or even really close to it. It seems that a few years back people started using CT2K.08 and they called it 0.6oz incorrectly. Either that or they were using CT1K.08 (0.51oz/yd) which weighs 0.61oz/meter2 and getting the units mixed up. Regardless, a 0.6oz weight of cuben doesn't exist and if I was buying cuben that was claimed at 0.6oz I would be careful to find out if it's CT2K.08 or CT1K.08 because CT2K.08 has double the spectra and it's a lot stronger. The 'CT' in the name refers to 'Cubic Tech'. The '2K' is the amount of spectra and the '.08' refers to the thickness of the mylar membranes on either side. If there's a 'HB' in the name then it's 'high bias' cuben which has spectra stands at 0, +45, 90, and -45 degree, instead of just at 0 and 90 like regular cuben. No one uses high bias cuben though...presumably because it's even more insanely expensive than regular cuben.
Once you understand how the naming works, you can choose cuben to suit your needs. More spectra is going to be stronger, whereas thicker mylar membranes are going to be more abrasion resistant (ie. good for groundsheets). 1.5oz cuben is CT5K.18. If you just wanted cuben that strong but didn't need the abrasion resistance then you could use CT5K.08. If you want the abrasion resistance then you could using cuben with the .18 mylar but less spectra like the new 1.2oz cuben which is probably something like CT3K.18 but that's a guess.