I completely get that defense is a personal choice. There are obviously variables at play that will prevent us from foretelling any particular player's future circumstances based on their decision to opt in/out of a city defense. Are there any players still around from the game's beginning in 2011? I ask because it seems to me that people that have been playing a long time could really provide some insight into whether mounting a meaningful defense was worth the space they gave up. Likewise it would be great to hear from players that chose to use little to no defense and how that turned out for them long term. Does anyone in retrospect wish they had done it differently or maybe you had to change your decision later? I'm just wondering if a 4-5 year window of time could provide a broad enough sampling that one could arrive at a consensus one way or the other. Possible? I do no know.
I've played since open beta began (before the us server opened) back in april 2012.
First of all, watchfires didn't even exist until Easter of 2013. Same with rogues.
To answer your question, in later ages watchfires are pretty irrelevant. I can clear 400% boosted defenses that are one age above me and only lose a couple units.
In the later ages, the only way to stop neighbors from attacking you is to either max out deal + sbc + have 100+ watchfires... or just collect on time and choose defenses that counter the attacker's units.
I did build the two defense GBs, have them at level 5 and 6. I basically stopped leveling them a couple years back. I only have a handful of other defense structures, i.e. tigers dens and a couple watchfires for a total defense boost of about 33/70.
It's very rare for me to get attacked, but when I do get hit, my defenders kill anywhere from 0 to 8 units, depending on what the attacker uses.
My personal feeling is that the defense GBs weren't worth building, but since I did build them, I'll keep them around to level when I'm bored.