I bought a D1 500 Air kit last year as I wanted decent light for the winter months. At that point there was a fair amount of discussion about the flat frosted glass that is on the D1s. I ended up buying the replacement cover which looks like the 300/600 series in order to use a beauty dish and magnum reflector.
My sense from the discussion is that the older units had a bit broader spread which was modified by Profoto reflectors in a specific pattern which everyone liked. It appears that the quality of D1 light is very similar to the 300/600 in color consistency and output other than the slightly more narrow spread with the flat cover.
300/600s have a reputation for great quality and long life...as long as you set the correct voltage on them...US v Europe.
Should serve your purposes well.
Bob