Maybe it's just phycological, shooting lead #4,5 or 6s at turkey for years. My patterns at 40 yds with 7.5 TSS are better than my lead from my 12 ga. so I wouldn't call it counter productive. Would love to shoot 8s or 9s if I could convince myself they can kill (yes I've seen the data). Thanks for the info.
Counterproductive is probably the wrong word. There are about the same number of pellets in an oz of TSS 7.5s as there are in an oz of lead 6 (~220). But TSS 7.5s will undoubtedly outpattern and outperform lead 6s. So you are gaining something over lead. But from a physics and performsnce standpoint, there is just no argument for 7.5s over 9s for turkeys.
I completely get the psychological aspect. I started hand loading tungsten in 2013 before it was sold commercially. Couldn't make myself shoot 9s. Thought about loading 7.5s but those who had more experience explained basically what I'm explaining here. Still couldn't do 9s, so I loaded 8s for a couple years. Eventually I started wrapping my head around it and moved down to 8.5s. Finally, 2-3 years ago I bought 9s. Last year I even shot one with #10s out of a .410.
Shoot what you're comfortable with. It took me years to become comfortable with 9s, and without a doubt, 7.5s will kill turkeys remarkably well. But 7.5s versus 9s is ultimately a choice between 310 lethal pellets or 540 lethal pellets going downrange.