Truce Tower is okay, but still something of a luxury. It's not really going to help you make back the goods you used to build it in the first place, nor will it really get you the goods to build other high GBs. I see it as more of a GB that supplements regular goods production. I can get maybe 5-10 of each SAJM goods a day just from auto-aiding my friend list, and while that isn't a hell of a lot, I can still build up a small supply of those goods and trade them down for stuff I need. Yes, I can get more goods by direct trading, but it's not completely useless either. By the space ages though, it probably will be less important though.
I've long thought that it's not worth building a GB only to tear it down later, but the reality is that some GBs that used to be very good are much less powerful these days from powercreep. I got rid of my St. Mark's too because I didn't need the coin boost, and the unrefined goods were a joke. There was no reason to keep a 6x6 around for 50+ goods from three ages back that I no longer need. I should probably dump my Atlantis Museum too, but that's harder to replace. Royal Albert Hall is another candidate for deletion, though I'll probably keep the LoA for now. Never bothered with the Flying Island because I don't like doing settlements in the first place. Another GB that was considered a must have but is powercreeped is the Innovation Tower. Event buildings make so much population and fp that the Inno's worth quite a bit less these days.