I do belive so and the maker comes off as an ass IMO but they are just incredible.
GDEMU is the more functional unit. It has a GUI and improves load times but dreamcast games are easy to find and burn.
Rhea/phoebe have no GUI so selecting games is a pain. I only keep 2 games on the card at a time because you manually press a switch to switch games.There are no improved load times either. Good Saturn rips are hard to come across too
The RHEA got a menu back in the winter. It works well, and alleviates blind-switching of games. I also find load times to be improved on the RHEA, especially with stuff like SOTN and fighting games. (Anecdotally at least.)