The drive system in the Honda HRC216HXA is a shaft-drive, fully hydrostatic design.
The HRC216 features the GX160 engine and it has has a special Power-Take-Off that turns a rigid shaft and operates a pump inside the transmission. The pressure created is then modulated by the controls on the handlebar, and causes the rear shaft/wheels to turn. There are no belts or pulleys on the HRC216.
All other current Honda self-propelled mowers use a belt-drive design. Those with the SmartDRIVE controls use a cone-clutch, and will this year move to a slipping belt arrangement. Two of the HRX-series models use a hydrostatic-style transmission, and the third is SmartDRIVE.
I'll speculate that you have not seen a Nexite deck commercial model from Honda are probably:
• the commercial-grade hydrostatic transmission in the HRC won't fit the current Nexite deck
• the commercial-grade hydrostatic transmission requires a shaft-drive, which is not a feature of the GCV190 engine found on the other Nexite mowers.
I don't think any of the belt-drive transmissions are would pass Honda's commercial durability standards. Fine for homeowner use, of course.
Caveat: I work for Honda, but the preceding was my opinion alone.