Yes as a MacBook Pro (Retina, 15-inch, Early 2013) owner, I'm disappointed that the late 2013 supports Big Sur yet the early 2013 doesn't. Comparing specifications (from Apple's web site) the significant difference [significant to my eyes ...] appears to be in the graphics processor. See below. Any other thoughts?
Early 2013:-
Processor
▪ 2.4GHz quad-core
▪ Intel Core i7 processor (Turbo Boost up to 3.4GHz) with 6MB shared L3 cache
▪ Configurable to 2.7GHz quad-core Intel Core i7 (Turbo Boost up to 3.7GHz) with 6MB shared L3 cache or 2.8GHz quad-core Intel Core i7 (Turbo Boost up to 3.8GHz) with 8MB shared L3 cache.
▪ 2.7GHz quad-core
▪ Intel Core i7 processor (Turbo Boost up to 3.7GHz) with 6MB shared L3 cache
▪ Configurable to 2.8GHz quad-core Intel Core i7 (Turbo Boost up to 3.8GHz) with 8MB shared L3 cache.
Graphics and Video Support
▪ Intel HD Graphics 4000
▪ NVIDIA GeForce GT 650M with 1GB of GDDR5 memory and automatic graphics switching
▪ Dual display and video mirroring:
▪ Simultaneously supports full native resolution on the built-in display and up to 2560 by 1600 pixels on up to two external displays, at millions of colors
Late 2013:-
Processor
▪ 2.0GHz
▪ 2.0GHz quad-core Intel Core i7 processor (Turbo Boost up to 3.2GHz) with 6MB shared L3 cache
▪ Configurable to 2.3GHz quad-core Intel Core i7 (Turbo Boost up to 3.5GHz) with 6MB shared L3 cache or 2.6GHz quad-core Intel Core i7 (Turbo Boost up to 3.8GHz) with 6MB shared L3 cache.
▪ 2.3GHz
▪ 2.3GHz quad-core Intel Core i7 processor (Turbo Boost up to 3.5GHz) with 6MB shared L3 cache
▪ Configurable to 2.6GHz quad-core Intel Core i7 (Turbo Boost up to 3.8GHz) with 6MB shared L3 cache.
Graphics and Video Support
▪ Intel Iris Pro Graphics
▪ NVIDIA GeForce GT 750M with 2GB of GDDR5 memory and automatic graphics switching
▪ Dual display and video mirroring: Simultaneously supports full native resolution on the built-in display and up to 2560 by 1600 pixels on up to two external displays, both at millions of colors
