I think it's a bit of mental exercise of ensuring that we talk separately about what each system does in practice—the empirical aspect—and then about our normative arguments about each system. The normative arguments about each system are the criticisms one might make about the effects of these different values that each system has, and some of those criticisms are more or less empirically valid. I'm not sure the comparative evidence tells me that PR systems are inherently unstable. I think you have to cherry-pick a couple of countries to be able to make that claim, whereas many of the countries with PR systems are perfectly stable and their systems are stable.
On the flip side, if your argument is that PR systems tend to have the capacity to produce more narrowly interested or more ideological and even extremist parties, then we do see evidence of that. We have to separate fact from fiction. I think the starting point is speaking to Canadians about what each system does, what it looks like, how it works, and what the effects are empirically. We can then get into the debate about values when it comes down to looking at these alternatives and what order we are ranking values. If proportionality and vote equity are at the top, then we might look at MMP or STV systems. Are we concerned about accountability? That might fog things up a bit.
I think we have to be clear about separating the “what is“ from the “what should be”.