Infinity RS 1B - How does the 'old dream speaker' compare to today's speakers?

The speakers in your pic aren’t RS-1Bs. It’s the big IRS system.

I owned the RS-1Bs for years, then traded them in for a set of IRS Betas, which I still enjoy and think is a much better speaker overall.

I mean the 'big' system Infinity Reference Standard IRS. 

I have two pairs of RS1B woofer towers, and I have been listening to Infinity EMIMs and EMITs for decades. They are still pretty good but I needed a change after all these years so I have been listening to other speakers. I really like my Triangles and just stopped short of ordering a pair of Signature Deltas.

Have several irs infinity have rebuilt some of the ribbons rewired and changed to electronic crossovers.they are tri amped.that is one amp for woofers and one for mids and one for tweeters. 200 hz to 5000 hz for mid frequency range.5k above for tweeter. If you buy a used set plan on doing this.new speakers many of which have ribbons for mids and tweeters.the ribbons are faster in response mass is momentum x velocity and the ribbons ie kapton or metal are light and move fast and are responsive because thier weight. Some have lower spl so many in line array increase spl. They have good horizontal dispersion but poor verticle.one more reason for line array.i like the sound of ribbons some like cones.find someone who has a set and listen.enjoy the music.