I'm honestly not feeling the power gap right now, or at least not where it matters (in da jibblies).
Sure, I can't go anywhere solo without getting ganked, but I have never setup for duelling anyway so this doesn't bother me. It's not a single player game.
In a group I still think organisation and teamwork is more important.
I've ran about 20 odd scenarios with assorted guild premades in the last couple of weeks and have perhaps lost 2 of those*. On one occasion we had 3 out of 5 players sub-70 (me included) and we won 7 out of 7, including versus well-known Destro premades. The group was SM 52, SM 59, BW 68, WP 83, IB 83 - hardly the pwn all group of the century. Idly roaming about with the same group between Scs we encountered 2 RR90 players, a DoK and a Marauder. We killed them without any trouble, as you would expect 5 v 2. They were not the "group-killers" of internet fame.
This is not me trying to be all leet and knowing, not at all. I am just saying that, from my experience, which is all I have to go by, I do not feel that being outranked and outgeared means an automatic loss, which is the impression you get from reading the forums.
Perhaps the gap is not wide enough yet. I get the feeling that whilst many individuals may be RR90+ already, guilds/warbands on average, are not. Maybe some are just beginning to reach a position where they have more members online than not hat are RR90+. This may start to change the picture entirely, but I'm not so sure.
Sovereign Gear provides some excellent bonuses that significantly benefit a group. Doomflayer and Warpforged may bring great individual power but my money is on Sovereign retaining it's importance to a warband's overall performance, with DF & WF giving players more choice between group utility/synergy and all-out raw DPS/heals.
* - to put this into context a bit, in the 2 lost scenarios we were convincingly beat and hardly seemed to make a dent in our opposition whilst they creamed us, so yeah, with all things being equal I am not dismissing the importance of gear and rank.