Sorry, not sure I follow...
Infinity had what I considered a premier line with the IRS at the top, way back when I was more involved in audio (say late 1970's to early 1990's). The company almost disappeared, then was reborn as more of a midrange but competent line, then became more of a low/mid range speaker line with the exception of their car stereo speakers. Maybe; I quit following them (and much of audio) around the late 1990's/early 2000's as other facets of life took over. This is all just my opinion so could well be wrong.
I am really impressed by Gary Kohl and crew creating Genesis from the ashes of Infinity.
What I meant was little is known of the IRS series overall
when I planned on doing a complete restore of my own set I went digging and spoke and emailed plenty of folk
While no one knows or took time to make notes on the line this is some stuff I put together
the first gen was IRS 1 then 2 then 3 never was a 4 bad luck thing in Asia so I was told
now what happened to 1-2/3 well Arnie has a good thing at making owners to update them.
I’ll bet he was making good money on this alone
the smaller model RS1 and 2 also got updates
I own a pair of RS1b as well
while they have a similar look they have very little in common
the RS was a 4 way IRS are 3 way
RS was a combination of line and point source
only the woofers were a line source
back then since Arnie was the leading authority on audio
he had owners swap a fairly new stuff to get upgraded
RS 1 became 1A then 1B imagine two updates in 1 line.
the IRS did this too. but I’ve never seen any as IRS 1/2/3 only 5 or 3
IRS 3 has weaker magnets
5 has much more powerful ones
some think it was sound , while some say they could hear it
I can say newer ones played louder at same power
he wanted more efficiency as most loved tube amps
so Arnie asked the amp maker to improve his woofer tower amps
old 1/2/3 were 1500 watts
new are 2000 watts but now work on lower imp on woofers
doubled up all
2 power transformers
Doubled output devices and capacitors
the maker had some funny stories of Arnie
lastly how many
well story goes as follows
the maker was asked to make 100 pairs of new amps
a total of 200 pcs
Paid him and he delivered them
now how many are used no one knows
serial numbers for IRS V does not help
but imagine 1500 pounds 4 towers new amps
new magnets on 100 drivers
12 new woofers
Never could find out for sure if they were shipped
or someone came to you.
best guess is 70 pcs or so.
genesis owned now by Gary has improved and in many ways re engineered the line.
I’m very grateful to have met him
Arnie sold Infinity and created genesis
Gary I think hired Arnie and Paul of PS audio to make him a set of speakers
then bought the company
Gary is hands down the most valuable, informative
And presenter of audio.
some of what audio rooms do now is as him
how he can explain why is a master class on audio.