Ten years ago I was a part of a Sunday night group that was started by the pastors and was loosely comprised of people beyond university but before kids. To me, it was church. We gathered regularly, had some food together and had a discussion of some sorts. It was so great for me I quit Sunday morning services. A year or so later the group was still going strong and in fact had expanded to the point where we split into to rooms during the discussions to keep things easier to participate. The one thing I missed about the usual Sunday morning services was the inter-generational interaction and also being a part of a larger community. So I started going back - though I would only show up at coffee time after the service.
Over the past 3 years my wife & I have been on a journey that has ended up being remarkably similar. At first we just quit church and just enjoyed rest, relaxation, and our own devotional time. Then we joined up with a house church group for a while. Eventually that faded away and we tried things with a couple we had met through the house church. I think what we discovered over that time is that the small is beautiful but it can be fleeting. Large groups have stability and diversity but don't have the intimacy.
Now we are back to a usual Sunday morning church service. Whereas the previous church we were at up until 3 years ago did not have small groups this one has a big focus on them. We are just starting the groups now and look forward to them being the cornerstone and the Sunday morning gathering the addition. As we look into the following years I would see us being regulars at the groups and less regular on Sunday morning. I believe both with ebb & flow.