example, a 800V 16A
That is indeed only negligibly true, at least in general, with semiconductors other than MOSFETs and Schottky diodes, as long as you stay within a specific general chemistry (such as silicon as opposed to silicon carbide or germanium or gallium arsenide).
(Actually, this voltage drop variation with voltage rating is slightly true with bipolar transistors. 1000 volt bipolar transistors have significantly higher saturation voltage and generally less gain than ones rated 60 volts or less.)
I expect negligible to minimal difference in voltage drop between a 200 volt triac and a 600 volt one.
- Don Klipstein ( snipped-for-privacy@misty.com)