Although better motion than the xR4 it is still difficult to sustain elevated heart rate on any recumbent elliptical.
The xR6X is built on a completely different platform, which is a good thing because the xR4 platform is terrible. The 6X moves the drive forward, giving the desired fluid ellipse motion while offering the position of a recumbent bike. However, everything comes at a price and expect to pay nearly $1000.00 for the 6X and $1500.00 more for the tricked out console of 6Xi. I digress, there is nothing tricked out about any of the consoles Octane offers. Please keep in mind that as the 5k threshold is approached these Octane models become even less desirable as the Nu ?Step commercial can be had for just under 5k.