There are production strains of RIR that compete with the sex links of Warren/I.S.A. genetics groups.
Production Reds are hardly traditional RIRs, but nice birds that will lay 320 each of their peak two years.
There are also production version of the Barred Rocks, lighter bodied and bred to lay, but I haven't seen claims for numbers, but to call them production, they'd have to produce over 250, or I would avoid the label of "production".
Whether it sex linked or not, anything that is production level is going to be highly selected genetically for egg laying.
The sex link is merely crossing two production strains for parent stock. I personally don't see the difference in buying either the individual parent stock or buying the sex linked offspring.