I’ve had both. I had the 801 Nautilus speakers with aluminum Tweeters
Now I have the newest diamond tweeters on the latest 801 reference
build dates on the speakers are 23 years apart so I am definitely hearing more than just diamond versus aluminum but the newer diamond ones are better
You are in luck I actually have a pair of brand new aluminum tweeters from Bowers in the box that I kept as backups and I no longer need them so if you private message me, I’ll give them to you if you will just pay for shipping
I think they they are the same tweeters as the 802, but you might wanna check that just to make sure
Nick