Check the weight difference between SR and R 12. I think it's about the same as the difference between the current SR and Chorus. Chorus has historically been released at the same time as Record for the history of ergopower, and not trickle down, just more affordable, and usually advertised as having the same quality and function as Record, just heavier and more affordable.
1992 - Ergopower introduced, Chorus group officially uses Record ergopowers (same part listed as part of the Chrous group), Chorus gets its own version in 1994/5.
1997 - Record and Chorus 9 speed introduced
1998 - Record and Chorus get new hood shape
2000 - Record an Chorus go 10 speed
2007 - Record and Chorus get QS shifting
2009 - Super Record, Record, Chorus 11 introduced
2015 - Super Record, Record, Chorus go revolution
Chorus and Record have historically always been joined at the hip for the entire ergo era. The only thing that has been trickled down over time is materials and cosmetics as those got small updates for both Record and Chorus. Chorus was never time delayed trickle down a year later like Ultegra. It was just a more affordable version of Record always being released at the same time. Chorus not being released with Record is new and nothing like what they've done in the past.