I like Mike Schreiner, but I don't think jumping parties works out for the vast majority who do so, the vast majority of the time.
Its simply seen as something disingenuous or disloyal; ie. "Were you ever truly a member of party 'x' " .
I also think it doesn't tend to work out well for the acquiring party either. Not only for the reason above, but because it suggests (rightly or otherwise) that the party is so weak in bench strength that it needs to
grab someone from somewhere else; and/or that its all about gaining power (which it usually is, but its not supposed to look that way)
I tend to favour the idea that party leadership races should be turned on their head by prohibiting 'new members' from voting. Currently, the way these things tend to work is that prospective leaders go out and sell thousands to hundreds of thousands of memberships, which in turn, presumably go to to people who will support the campaign that sold these to them.
So people who were not remotely interested in the Conservatives, or Liberals or NDP etc. a week, month of year earlier are suddenly empowered to decide the future course of that party.
That seems like a way to lose faith with your core supporters to me.; and its a process very open to abuse/manipulation.
Why not require someone to be a member in good standing for at least 2 full years prior to a leadership election in order to vote?
In that same vein, it hardly seems reasonable that someone should be running who was not also a member for at least 2 years.