Does anybody have a large amount of experience with any of these engines?
Well I don't, but I'd like to point out that Youtube, for the last couple of years, has exploded in a ton of tutorials for anything you can possibly imagine. Watching some tutorials might answer some additional questions:
I don't know about you, but I've learned tons from watching youtube tutorials alone and I also find these very useful when trying to figure out if something is interesting or not. It's a tool in the toolbox for when you want to find information. Going to someone's playlist and looking at the overall array of videos that they've got, can also be a way of shortening down the time you spend watching their stuff (since you don't need to watch every single tutorial video just to get an idea).
Hope it helps.