KMadCandy
giggling permanoob
Lightbulbed GSs provide a ton of early game beakers that can be leveraged for early liberalism which can be leveraged for renaissance military tech which can be leveraged to expand your empire which translates into even more overall beakers. People always forget to factor in lightbulbed GSs and although a CE will have a gpfarm, a SE will have more GSs overall and will generally have them in greater numbers EARLIER as well.
futurehermit knows that i can compare different difficulties easier than he can since i swap around a lot

if you're playing SE and lightbulbing techs but not beating up everybody at once, you can trade some of your lightbulbed stuff for techs to backfill things that you skipped. that can get you zillions (approximately) of beakers for your lightbulb. that tends to work better on higher difficulties than lower levels, because the AI has more techs available to trade. even without the pyramids, once you know how to work it you can get ahead of at least some civs to have trade bait. how many can depend on difficulty, who the opponents are and what mood they're in, what the weather's like, blah blah.
of course on settler you won't really need to get zillions of beakers for one lightbulb, you'll be so much faster than they are that even without trades you'll have tanks when they're defending with longbows. but it's a PITA wasting your own time researching the stupid pre-reqs to get what you really want, even when it takes just 3 turns or whatever. so altho they tech faster the higher you go, if you haven't pissed everybody off yet you can use that to tech faster yourself. which makes it more exciting, at least for me sometimes. and sometimes, i want to beat up longbows with modern armor.