I belong to a Guild of about 160 that has both a morning and an evening meeting. We have one set of officers, which does limit who can serve to those that can make both meetings pretty regularly, but they do cover for one another too.
Our programs usually mean a speaker needs to commit to both meetings. Which means that if the speaker is not a Guild member, that some members of the Guild need to treat to lunch, squire around to the local LQS, antique stores, etc. But we have a group that work after the morning meeting on community service projects and sometimes the speaker will stay and participate.
Most of our workshops are held at separate times than the meeting/programs. I'd say that about 60-70 members attend the mornings and 30-40 in the evening--so like all organizations, there are about 25% of the members that are not very active in participation, but still enjoy the "drop in" affiliation. I think that anytime you are a new member of any organization, you have to make an effort to get involved in order to get to know people--smaller size groups mean it can usually result in knowing everyone fairly quickly, but that doesn't mean larger groups are less friendly.
and larger guilds can muster the resources (both $$ and PEOPLE) to tackle big service projects, shows, etc. So both have advantages--it's all in how you look at it.