Not the Rimowas I have seen. Sure the Salsa Air is light, but it is a one pole design (annoying if you want to stack), but the others are much closer to the weight of Ballistic nylon bags, which tend to have better organization and features (eg, suiter). In my Tumi carry on, the suiter is removable, bringing the weight even closer.

Also, the Rimowas sold as carry ons do not strictly meet the 22x14x9 sizer requirement for many airlines; they are generally too wide.

Finally OP also asked about briefcases. Tumi briefcases are great; i for one am definitely not carrying a hard briefcase.