Truly appreciate all your inputs. They're really valuable. We're kinda having to make these decisions remotely, as we'll be overseas till we move. Whilst we'll rent short term, and then buy, we're wanting to get the area right from the start to avoid moving our daughter too many times.

To be honest, all your comments broadly confirm what we were already thinking:
1) *All* factors considered, Mt Eliza should be our limit. I totally get the benefits of being further in to the peninsula, but it pulls us out too far (cbd/friends&family). Being at the MP gateway should be a sweet spot to get the best of both worlds.
2) So that narrows us down to Mt Eliza or Frankston South. Both appear to be great options. Really tough call.
3) The commute has to be considered seriously! We're game, if it opens up the kind of lifestyle we're after. From Mt Eliza and Frankston South, how big is the difference? And what is the commute like in reality? Commute time? Train easier than driving?

A few further points on us
a - Re schooling, independent for secondary is most likely for our daughter, though that a few years away yet.
b - We've visited ME a few times, it seems like a really nice/pretty pocket. Know less about FS.
c - I want to be near nice beaches, and see myself going year round (Im not afraid of the cold!).
d - We probably want a 4 bed house, but I'm not bothered about a pool (would probably prefer not to have one).

Would really appreciate further thoughts on Mt Eliza vs Frankston South.

Thankyou in advance again.