Whenever you copy a mutate creature while it's on the stack, like with Volo's ability, the entire chain of mutate abilities will begin again when your copy resolves, giving you so much more value than normal
(In fact, weve so far already implicitly assumed some rudimentary player strategy: namely that if we can play a land, we do so.) If we're to account for all these different factors, its going to be practically impossible to get an analytical answer, i.e., an answer in the form of a neat little formula like the distribution function of the binomial or hypergeometric distribution
Both versions are equally playable in tournaments
Now I read the cards and think "beautiful cards, beautiful cards!" (who ever gets that reference - here is your cookie )
However you choose to do it, the end result will be a board full of worryingly large Insects, with Mazireks flying ability suddenly becoming a huge problem for your opponents as it crashes in for commander damage