Fellow lens designer here, great writeup and spot on. I have often used both these forms (as well as the general Petzval form) as the basis for high performance imaging objectives. One additional comment on the Sonnar vs Double Gauss I’ve found in designing with both is that, while the Double Gauss form seems to have higher potential performance, the Sonnar form often holds up better when tolerances are considered. Stated another way, the Double Gauss requires tighter tolerances to maintain a more consistent level of performance in a production run than does the Sonnar.