My 1948 Raleigh Record Ace has round section fork blades, and it's definitely a road bike. I haven't noticed any abnormalities in the handling.

I understand why round blades would be stiffer side-to-side while D or elliptical blades would be stronger front-to-back, but I really doubt it would make any difference to someone of my weight, and I am disinclined to think it would make a difference to anyone. Bicycle designers and theoreticians often get an idea about something or other and proceed to base all their designs around it, without ever really testing them properly. Whether this is such a case, I don't know; but it sure wouldn't surprise me if it is.

As I recall, that Kolin/De la Rosa book is full of statements like "Signor such-and-such believes blah-blah-blah and therefore designs all his bicycles to conform with this principle."