If you do not start with Alpha it is very hard to get the GLB. It is not a lock, even when you do start with Alpha. I would expect to do about 80-20 with and about the reverse without Alpha to start.
It would be less, but sometimes they do not research Lit for a long time and that gives me time to research it.
The next issue for me is that they seem to race for Education, once I make the GLB. Maybe that is just my paranoia. I have never seen the GLB get me into the IA at any level. Now I do not use any of the gift the town with it and take it back stuff.
I would consider that an massive exploit. Capture is not much of an option in any Sid game I recall. This is because it is seldom built close to me and whom ever makes, they will be tough so early, if they managed to built the GLB they are probably one of the top dogs. I also need Astro to reach them, if they are not close. This tends to mean I need ED.
I have had close nations, that I could jump with a small stack of galleys, but they have to be close, so I can run back and forth to get enough units in place, before disaster.
I have never built the ToE at Sid. That is probably some what due to my unwillingness to play nice. I do not try to keep them happy with me. I played one Pan game doing that and almost cried from the boredom. I quit as it was just no fun for me.
It is no problem to have a late GA, that I do most of the time. I am not going to build much in the way of wonders, just read about them. The early UU is only for barbs (if in the game) or back up in case of a big surprise.
I do get some of the Modern Age wonders as by that time I have a massive amount of land and towns and fear no one. Just grinding out those still around.
The only time I tend to get an early GA, is on a continent map. There I will surely be fighting for my life early. I like Smoke for those games. Can defend and can attack and can get slaves. Can get eliminated too, but then any nation can.
I normally play with only the Domination turned off, as I want to conquest them and they are not gong to win by domination or conquest anyway. If one of them got to domination limits, I would be long gone.