Unfortunately I have not impressed you much with the records I have given to you.
I have seen Hewitt/McMillan and was impressed. They surely were one of the best doubles but never No. 2. Hoad/Rosewall were stronger, f. i.
I have already written that in the first three open era years H/M lost deciding matches in the majors: to the three big Aussie formations plus even to Okker/Riessen.
They dominated only after the best doubles duos became old or had retired.
H/M won many South African titles with poor competition.