Also, I have never listened to Pompeii without watching the movie. So it's a whole different experience compared to Ummagumma.

You guys should expand yourselves a bit and find some boots where they performed ASoS. While Pompeii and Ummagumma are great versions, they're not the only great versions. Ummagumma and Pompeii were professionally recorded, so they played to that fact. The shows where they don't know they're being recorded (well, I'm sure they knew the shows were being booted, but it wasn't like there were mikes and camera crews in their faces), show a bit more spontaneity, maybe.

I don't know why I hate bootlegs. I'll give them another shot

I don't know why you do either. Bootlegs are amazing snapshots of the band at that moment. Far better in some ways, than studio albums. They're raw, there's no studio polish and processing, and you hear exactly what you would have heard had you been standing or sitting there watching them.

One thing I've found quite hilarious -- on the Animals tour, David's voice was just awful singing Welcome To The Machine, and he very seldom was able to sing out the whole line at the end. However on the MLoR tour, he sang it 100x better. By then he was 10 years older, too. Hmm.

IMO, David's voice got better with age.