Will a Schroth QuickFit Pro harness pass tech?
The Solo rule book allows for a four point harness like the Schroth Quick Fit Pro (https://www.schrothracing.com/products/quickfit) but I see the guidance for passing tech at Nationals refers to the GCR rules which don't allow for a plug-in harness.
I have an old 4 point. Mine is just to hold me in place better. I think the key here is that it isn't required, at least for street cars, so there are no safety standards such as expiration or mounting over a harness bar that apply. I have not explored the GCR on this matter but the car has passed National tech multiple times in current configuration. I'm not sure if Howard Duncan is still the go-to guy for this info but you could look him up (I'd phone SCCA at this point) and ask if you aren't sure.