Got the two Modernas 7+ months ago. Got the Moderna booster three days ago. I asked about the Moderna relative doses after an acquaintance who works in the field of international immunology mentioned Moderna's second regular shot was a little heavier than it should have been.... which may account for why so many had a flu-like reaction to the second shot, including me. I was really sick for a day after the second shot. I also asked about the mix and match possibility with Pfizer. The local "shot administrator" said the more effective booster is Moderna no matter if Modern or Pfizer were the first two shots. Also said the realive doses for Moderns is: 50-50-25. I was only moderately sick the day after the booster with aches, headache and slight fever. Anecdotally makes sense after being really sick after the Moderna second shot.
As an aside, my 16 year old stepson and 18 year old stepdaughter have both had 2 Pfizer shots. I am certain my stepson had Covid mid last year with complete loss of taste for about 10 days but with no other gross symptoms. Except for part of the first semester of school last year, both have been full time, in person students, thank goodness! IMO, the remote, online learning (non learning cluster flp) school mandate is really nothing more than a perverse demonstration of political power at all levels of gov.