Woodshavings are a by-product of woodworking industries. The general hard or soft feel of the woodshavings usually depends on what type of wood those shavings were a by-product of. Therefore you can't always guarantee a bag or a bale of softer shavings. Also, don't confuse woodshavings with sawdust - these are two different things and sawdust is not used for bedding!
Compressed bales of woodshavings from pet shops and garden centres are usually good value for keepers of a small number of guinea pigs. For bigger numbers, large compressed horse-sized bales of woodshavings work out cheaper than buying several small or medium sized bales.
Guinea pigs as a species have a relationship with respiratory disease, and this can be aggravated by dust. Even the "dust extracted" bales have a level of dust that can aggravate.
Woodshavings get everywhere, especially during cleaning out. The flakes stick to clothes, carpet and furniture, and turn up in every corner.
The flakes of woodshavings often get stuck in the private areas of boars, this being very uncomfortable and potentially painful for them.
Never ever put a recently neutered boar on woodshavings. His wounds will be poked by the flakes, causing him pain and discomfort and possibly even infection.
Cardboard bedding is made from chopped up or shredded cardboard that has been dust extracted before packaging. Bedxcel, Finacard, and Ecobed (which is made from recycled cardboard) beddings are primarily used for bedding horses on and are cheap to buy in bulk, although both aren't the easiest beddings to find.
Cardboard bedding is soft for guinea pigs to walk and sleep on, and is also suitable to bed recently neutered boars on. They can eat the cardboard as extra roughage.