faction master rewards sure are a challenge, but prophecies bonus' were more fun.
i have a slow net, meaning i mostly load around a min or something around that longer than the others, meaning they will want to wait for one of their monks to load before starting - this did cost me some master rewards at some point, and im feeling kinda dumb that im the reason the team failed. ;(
with the time system, it depends on way too much luck in my opinion. for example, when i did the temple for my last master reward, and our ritual lord set spirits, and suddenly togo was stuck in them.
then there is the BIG problem of one going afk, or getting err 7'd resulting in the team falling apart. one goes, one follows, next one, and so on. in proph, you could do most of these with pretty much half the team missing, took some time and skills but it was still possible.
another thing in factions...
master teams:
War
War
MM
SS
Monk
Monk
Ele
Ele
space for anything else? not really. assasins are totally NOT wanted (which i really dont understand, i always love to take one considering they know what to do), rits..maybe if they are a rit lord and the mission lacks of monks (well, except eternal and gyala, very welcomed there), rangers..meh, can be better, maybe put them for one ele, or as trapper at gyala/eternal. mesmer? omgwtfbbq never -.-. i DID enjoy playing without MM EVERY SINGLE time in proph, even having a mes now and then, which is too rare already anyways!
the timer forced people to be even lamer. of course, you could just get a guild team, but looking at it.
my guild when only proph was out = everyone was helping everywhere
my guild when factions came out = nobody was helping, everyone was strongly denying master rewards.
i got my prot of cantha two days ago, and was forced to use those lame groups for 9/13 missions (not vizunah, henchies ftw, raisu, as i was helping guildies and a random pug, we still managed it, without mm, without ss, without a nuker, just because i was rushing and evading every possible thing lol

, zen daijun, and minister chos - self explonotary). its really depressing and was stressing and annoying me out more than any other thing in gw. chances for actually balanced groups? nope, wasnt even a slight chance for it.
short summary:
challenging? - yes
less fun and more annoying? - yes
>.>