I feel lucky that I've never had to search for a Modded server outside of my RL circle of friends. Having done far too much of that back in my MUD days (yeah, text-based RPG was my life for some years), the quest for the perfect server is often soul crushing.
That said, our group consists of a small number of dedicated players, with the majority of the group being casual passengers. Our lives are varied, so the variance between amount of play time swings wildly. The priorities of each player are also all over the map, which sometimes is a blessing, but leads to frustration as well. The good news is, if anyone acts grievously asshatish, we know where they live.
I have seen a number of server resets and pack changes - some justified, some not IMO. Because I have very limited free time to dump into MC, I often progress slower than my peers. Once they have reached the end of their deemed progression path, the server becomes less visited, until it is essentially a world for me to play in which my potato of a computer wouldn't be able to run on its own merits (I sometimes think NASA had similar processing power during the Apollo missions). Eventually, the consensus is made to begin again - blowing all of my hard work back to the stone age.
Unfortunately, I feel this would be an issue with any server I joined, as my free time is getting less and less free as life goes on. I've come to accept that I will never fully flesh out a world as some of our Community Showcase players have, even though I can see it in my head. As sad as it sounds, sometimes SMP isn't all its cracked up to be, and a SSP world would be more gratifying. But then, if I'm going to drop some free time into a game, it might as well count as a social event.
I didn't mean to derail this, as now that I reread what I have written, I fear I may have. I meant only to say, you're not alone. I feel your pain. Chin up. That Utopia is out there somewhere. Safe travels.