One of my friends(single lady) just took a trip from Luxor to Hurghada by bus and this is her report.
"Luxor to Hurghada Super Jet bus leaves from next to train station at 7.30pm every night, takes 4 hours with one stop. Hurghada to Luxor Superjet bus leaves Hurghada to Luxor at 8.30am every day, takes 4 hours with one stop. 45LE each way (non- Egyptian) and drops you back next to train station. You can only get tickets from 1 hour before travel." The bus was clean, had a/c and there was a toilet although she did not use it.
I guess the only disadvantage is not being able to get the tickets in advance.
PS she said "mention the hassle in Luxor started before the bus doors had even opened when I got back and the bus was boxed in by taxis!! That would freak anyone new to Luxor out big time!"