I have had little to be impressed with the grease that comes with most lower priced cartridge systems. That said, I have had a very good experience with the same hubs on Valvoline #614 red moly-sulfide grease. I have gone as far as 3 race seasons on such grease with no change in consistency(I still check every couple months).
Some hubs are very simple and sometimes even tool-free to remove and install the cartridges. Some(such as several Mavic designs) can be very tough or next to impossible for the consumer to work on.