Your modifications also produce an excellent cocktail, but a robust gin (e.g. No. 3 London Dry) or one with other notable flavors (e.g. Hendricks "Another", Drumshanbo Fig & Laurel, and I assume many others) I think can stand up to the equal-parts version. Also depends obviously a lot on the sugar content and strength of your vermouth here.

Looking forward to trying this with your recommended ratio and upon reflection realizing I really need to keep better notes. So many cocktails I've sworn to revisit and yet moved on to the next one. When the Lillet Blanc is gone will be time for more Cocchi. Note to self ... try this first.