I can't say I've done a tonne of research on this. In particular, one of the people I work closely with is Mr. Risser, who is speaking with you this afternoon. On that question I would usually defer to him.
My sense is that it doesn't necessarily create as much inner-party tension as is often theorized. An assessment of what it does for the politics is that it gives relief to some members of Parliament, or of whatever house of assembly it is, because it relieves them of the local constituency duties, which are important but I would say are overrepresented in our current system.
The only people with a responsibility to look out for national or provincial issues are often cabinet ministers, and they don't necessarily get rewarded for that at the polls. If you look at the electoral success of people who have been ministers in subsequent elections, they're often punished for it by voters because they haven't been in the constituency, so I think having some mechanism by which to reward those who focus on more broad policy issues is probably a positive thing. You can get that with the list representatives in an MMP system.