lets see, many points have been said already, but here is my view on this.

Pros: With just around 30 members there are less people to give out GNW packs compared to having 80 members. You also get the chance to plunder more people since they are not in your group anymore.

Cons: With less members it takes more time to build up the group fund. Also the with less members u get lower group activity rate, or is that calculated by something else? With less members you wont be able to fill up all the fields and if one or more of the "elite" members go inactive its harder. Also by kicking so many members you lose lots of potentials.