What harness are most using? 4 point or 5 point?
5 point, one of these
https://www.amazon.ca/gp/product/B000NZPK1G/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
I feel that the crotch bit is needed because it keeps things nice and centered by keeping that center lock where it should be rather than being pulled up by the shoulder straps where it shouldn't be.
First few days I was driving without it and it was great, but adding the harness you really become part of the machine, specially in slick shod race machinery.
I think for road cars I won't strap in, but take that F2004 in AC some place, strap in and its pure madness.