IMHO the impact of changes on core game rules (different rulesets) should be tested with the core games, that are the WWII v1-v6 Versions and Global1940 2nd Ed. games.

However to save some time one could exclude v4 and v6 from testing, as those are simplifications of v3/v5.

Of course I don't deny to test other great games such as those already mentioned in this topic.