I'm not sure how many of those who vote will have a clue how the new system works, I specifically looked it up but wouldn't have known otherwise.
I've not looked at the system atall (not affected and not voting under it.
But what are that potential impacts of voters not understanding it. Guessing but somebody voting along party lines is putting they "X"s against the party of their choice whatever the underlying counting scheme. Is understanding the system going to change how they vote? They might be a bit surprised at getting more voting slips than expected but holding multiple elections at same time is not that unusual (where you get multiple voting slips.
I can see people getting confused as to who their elected representative is but that's probably long after they cast their vote.
I have has occasion where proportional representation has been very useful. When living in France I have an issue needing to be taken up by an MEP and I had several different party MEPs available (thanks to PR/Mr D'Hondt) - Conservative I contacted showed no interest, etc. and it was when I got to my Labour MEP and he took an interest and started pursuing things.