We have a handful of Rogue Echo Bikes at our facility (similar to the Assault bike) and really like them. In my opinion the complement KB training well and make for a great pair. The Concept 2 rower is also great, so you will likely be happy with either. We chose to go with the Echo bikes as they provide a few more options, such as ability to use legs or arms independently of the other, and the nature of the constant movement of the bike compared to the drive / recover / drive / recover nature of the rower (which is great, that is how KB ballistics are, we just wanted something different than that to help get different stimuli).