How will you account for the fact that penals DO arrive LATER then grens and grens will always outnumber them?
I'd like to see this new 10 gren squad meta that you're talking about.
By mid game, grens are usually outnumbered by penals.
4x4gren = 16 gren models.
Doctrinally - 4x5 gren models = 20 gren models.
4x6 penal models = 24 penal models.