“many people switch allegience in the tory leadership campaigns which is what causes all the hoopla. In the tory system your first (only) preference can change at each ballot, in AV it doesn’t unless your candidate drops out in a round.“
Yes. This is true. But internal party wrangling is, I rather suspect, a messy and polluted game. The two systems do differ but I disagree that it is a fundamental difference: it is entirely incidental and immaterial.
If, as should occur in a general election, the parties and candidates all set out their cases up front, then the relative merits are set. The only reason for anyone to change their preference after any given round is if the policies materially change.
If you’re proposing policy changes between voting rounds then yes, there is a difference. But if there is no policy change then the benefit analysis will pan out identically each time and there is no need to build in a mechanism for people to change their mind.