My opinion on this has evolved over the past few years. As someone who came from a big lodge, nevertheless, I'm now convinced that Masonry is better served by having more and smaller lodges, versus my earlier view that it doesn't much matter.
Every lodge can provide some 20 to 25 leadership positions. Conversely, to lose a lodge means to lose that many potential leaders, and that a smaller proportion of the brethren are likely to exhibit the level of 'ownership' that leaders have.
I think one of the things we can learn from lodges in the UK is that a membership limit is a good thing. The typical UK lodge will cut off membership gains at 100 or 125, at which point the brethren are encouraged to form a daughter lodge. Sociologist Robert Putnam wrote, in his book Bowling Alone, how groups thrive with a level of intimacy and bonding up to about 130. Anything more than this leads to more fragmented relationships.
I think the *right* amount of membership depends on the number where leadership is sustainable, and where we are not struggling to fill chairs. North of 60 men, I suppose, and less than 130. It is also a useful lesson to draw from our British brethren that members ought to be given a summons to attend each meeting. The expectation must be set that attendence is required except with prior-approal. We're moving the dial on this issue here in the States, so this will be a struggle for a new-model lodge.
The impact on the Grand Lodge is that, if we can show how a 'smaller' lodge can nevertheless function well, we help other lodges stay in the game. They need not merge into a superlodge in order to survive.