I think that many of the key guilds should be 85 lvl guilds, and just reduce
the benefit at the higher lvls...that way, you could have a lvl 85 MASTER
barb, or maybe a lvl 50 pretty-damn-good-barb/lvl 35 decent crimson or
whatnot...make it so that variety can't max stuff, but also make it so that
you don't NEED to be max lvl in a guild to be useful...additionally, this
might allow it to be in tune to take extra backgrounds as well (for example,
spend 2 lvls for each lvl in a secondary background, 3-for-1 in tertiary,
etc)...
The problem with low numbers of guild lvls is that there is too much emphasis
on direct maxing things...by making every guild a lot of lvls, there will be
more variety in terms of where people decide to hop out of one guild into the
next, etc...(and, of course, there will be some sort of curve where the
majority of skills to be a general member of a guild will be available halfway
through the guild, and further lvls will give more power, but with diminishing
results).