New Speakers under consideration - but I’m afraid

The advances in speaker technology has been very large. Yes you have much to gain. The safest bet will be the B&Ws since you like their speaker sound and they are still very bass heavy. But a trip is still worth the time and expense.

I would read avidly about your choices, then make a trip to the states to confirm. With your knowledge of your speakers and auditions you should be able to extrapolate to your audio environment.

Well a 15k speaker today there 15 yo equivalent would be about 4k back then. Better is subjective for sure and you would need to listen. I had BW Matrix 801 vii for a while. With a monster amp pushing them they were just as good as most today. I’m not of the camp that speakers are night and day better especially comparing to totl from 20 years ago. 

Well a 15k speaker today there 15 yo equivalent would be about 4k back then.

That’s adjusted for inflation, but does that also apply to or account for the potential for increased performance due to R&D over 25 years?

If you like the B&W sound you are on the right track with the options you mention but you might like to add Focal to the list. Not my cup of tea but speaker choice is very personal and I prefer the more musical (less analytical ) speakers like Sonus Faber.

Why not stay with what you have? They are excellent speakers