This is an argument that gets made against a lot of PR systems—open list, STV, etc.—that there's party fracturing, because you're running against members of your own party. All the research I've seen, and that's by no means exhaustive, says that it's really not that big a deal in those systems.
SMDPR actually prevents it, because you're running against people in your own party but not directly. You're running indirectly. If I'm the local candidate in a specific riding, and all the party votes are grouped, I'm not running against you, and I actually benefit by your doing well. Everybody is trying to do better than the next person, but there's no situation I can envision in which suppressing the votes of somebody else is going to benefit you.
We looked at this, and one of the things we settled on, too, was to rank candidates based on the percentage of the electorate, because that does two things. One, it disincentivizes voter suppression. If you did it by percentages of the vote in each riding, then you would incentivize some candidates to suppress the votes of others. Two, it allows for variable riding size. But all the incentives under SMDPR are for you to try to get your individual vote turnout as high as possible, and also to try to get your party's vote across the region as high as possible. There's no internal competition in that way, because if you're trying to drive down the votes of other candidates in your party in other ridings, you're actually making it harder for yourself to get elected. Right?