IMO any twin vac machine looses too much performance beyond 50ft.
On long hose runs, vacuum lift (suction) will not be affected to any appreciable degree but because of the "weight" of the extra air being pulled on long hoses, combined with the frictional losses, cfm loss will be considerable.
Pump delivery follows the same rules. Psi will not be affected, but flow rate will be significantly compromised over longer hose runs. More so if running upstairs.
All of this means that longer hoses will deliver less water, so rinsing action is reduced, and cfm reduction means that water/soil is evacuated at a slower rate.
Slower or more passes will be required for rinsing and slower dry passes too.
50ft of hose on a porty will clean a pretty large house. Even with my van mounted system, I rarely need more than 75ft with 50ft of hose being the norm.
Safe and happy cleaning

The Ken