I found the heads/baseplate don't FrankenRazor well with techs. Scary blade gap with the blade straight 90% angle from the head. Never tried that shave... The handles fit though.
There are different Tech handles and New baseplate designs. The male and female threads have always fit well in every combination for me, but there are some cases where the top of a tech handle is too wide to snug to the bottom of a particular baseplate.