I've spent my KaW life growing up learning that SoSs were only good for stats and steals, that they hurt your plunder. I did not find this however, when I built some of my own. I'm not going to spend a lot of time explaining why this is important etcetera, so here's how I think it basically works. If you or a friend was in a situation that does not fit my theory, please comment. If the total spy stats you gain from all of your SoSs is above a certain percentage of your total spy stats, the SoSs give good plunder. Also, if the SoSs give high enough percentage of your total stats, they give good plunder. I have only 2 lvl 3 SoSs, and a lot of guilds. My SoSs give good plunder. This would put me in the "doesn't grant too much spy stats" section. Attack builds who's plunder suffered from SoSs would have a high percent of their spy stats come from SoSs, making the SoSs hurt their plunder. According to Vandalise, if 2/3s of your buildings are SoSs, they give good plunder. While attack builds would get most if not all of their spy stats from SoS(s), that would still be a very low percentage of their total stats, and therefore not grant good plunder. Again, if you know something is wrong with these rules, or you would like to make educated guesses as to the percents I mentioned earlier, just go ahead.
I heard somewhere if you have more than 3 SOS then it gives you good plunder? Idj what to believe hah!