Over the past year, I have withdrawn from large groups for the following reasons:-
The larger the group, the greater the chance of giant egos to match and with egos comes troubles.
The larger the group, the more impersonal the beast becomes.
There is to be found in large groups a distinct barrier of them and us; much has bee written about Trad Vs Indie writers and how THEY look down on US. This goes for large groups too, from personal experience I have found that large groups are great if you are a selling author; have money; pulling power or connections to boost books. If you don't, then they don't want you and WILL ignore you at best.
Another item I had seen in action is when a former Indie gets in print, they tend to look up on those with ebooks as inferior, again I talk from experience. Maybe these are not changes at all, but the real person exposed; as with alcohol, it doesn't change you, all it does is lower your barrier to let more of what you are inside out.
As much as I would wish to be in print, having seen the vast changes it brings in personality; I hope I won't suffer these.