I disagree... the difference between looseball and cartridge is felt on the road IMO if you're actually going fast and throwing in hard accelerations. But the difference is not noticeable at all between okay cartridge bearings (Formula) and better cartridge bearings (Phil), atleast in my experience.

If looseball bearings didn't make a difference, what reason would there even be for their continued sales? Hell, Dura Ace road hubs are all loose ball today, they're just well sealed.