I think the main thing is turken vs "regular breeds"- not bred for production. Example, a turken may be a better layer than a wyandotte or campine. I have noticed that my turkens start laying much earlier and longer than blue laced red wyandottes, lay bigger eggs than the wyandottes and so on.
But, production bred birds were bred for 'maximum production by the professionals' so they will be better layers in general than almost anything else. They have the bonus of being selected and bred by people with the supermarket egg production in mind.. turkens did not get that kind of attention, so production breds will do better.
If turkens *did* get that sort of production breeding attention, they'd probably easily be as good layers.
as is, turkens are good for backyard dual purpose breed. one apparent con about production bred birds, especially the "sex links" is that some hens can run into egg laying related problems.