Lansing went from Altec to found JBL. There was a lot of shared technology due to the whole egress/founding thing. Lansing (Martini actually) brought many of his patents with him. Altec was originally All Technical Services. The only common thread between them was James B Lansing.

As for changes, the biggest have come in the form of tweeters. 20 years ago, tweeters sucked. Now, many suck, but, there are some good ones out there. Otherwise, computers and computer modeling have changed a lot of things. Companies can now make drivers specifically for a speaker with different voice coils and motor geometrys to do very specific things. An engineered roll-off allows the use of a simpler crossover, less is more. I hold out more hope than you, but the contamination of marketing and loss of interest in quality will be audio's ultimate demise. Sony is already finding that out with SACD. The "revolution" that they are going to cram down everyone's throat in a couple of years due to lack of interest in better sound. MP3 is the "hot thing", and that is only acceptable at best as far as sound quality goes at the highest bit rates. There just aren't many out there who care anymore.

I've known a bunch of old guys with "Voice of the Theater" systems. Never any Hartsfield guys though. All that fancy wood stuff went away when the head wood working guy died. Sorry, I don't recall his name. But speaker "sculpture" had pretty much died by then anyway.