Looks like more, but it isn't. He just broke down his three sources to make it look like he was a diligent busy little bee.
One is a Ravitch article that cites one presenter at a conference. His PPT is a bit confusing, to be honest, on one point: One slide says some studies showed "Possible gains from competition of about 1-2 percentiles or about 1 point on international tests (PISA, TIMSS, PIRLS)." But then he shows and cites for Ravitch large losses on these tests. This is after he discounts the worth of GPA or national standardized tests as showing anything useful, since teachers get the tests ahead of time and grade them--the assumption being, I guess, that this means they can teach the test or intentionally misgrade them.
But take the PISA as an example--I choose it because it's first in the list and I don't want to take all day rummaging through international testing protocols. It's normed and scaled for each testing cohort. It's not norm referenced or criterion based. 5000 kids take the test, their average score = 500. If you do average, you get a 500. If average was a score of 89%, that's 500; if average was 39%, that's 500. If your country's students do 5% better on the test than last time, but other countries do 10% better, your country's PISA scores drop like a stone.
I suspect this is the "possible gains of about ... 1 point on international tests (PISA...)" compared with hefty declines in PISA scores. Maybe not, in which case I have no idea how both A and not-A are right. Hard to know what Ravitch's one source for those first three claims actually means in this case.
The last citation in the OP, though, uses GPAs and such and finds no decline. That's why the one researcher had to dismiss through innuendo such data. It didn't support his argument, he had no counterclaim for dealing with it, so he just sort of mentions it and sets it aside.
As for the rest, yeah. Increased stratification, check. Esp. in Sweden where, in the '90s the number of immigrant communities increased and their numbers increased. Whether this would have happened without vouchers ... Well, it probably would have. Same for economic segregation, as the result of political changes. Post-hoc arguments are so much horse post-hockey.
Good teachers prefer to go to better schools, with the proviso that some of those private schools would have been ethnicity- or religion-based, and so some established, experienced teachers wouldn't have been eligible. This happens anyway whenever you get any kind of segregation. I assume that I know what he means when he says "better teachers"--more years teacher, greater number of advanced degrees. He may mean "teachers whose students show, on average, significantly more than 1 year's increase in academic achievement in one academic year". But for that he'd have to rely on GPA and national standardized tests and that would be inconsistent, so I assume he doesn't do that. Most often "better teachers" is equivalent to "teachers of better students."
In the end that writer ends up by saying vouchers increase choice (+), have no net affect on achievement (0), is a negative for equity (-), and is indeterminate with respect so social cohesion.
Except that it's likely that equity was going to change anyway. It boils down to whether or not you like vouchers and can put up with the occasional scandal (which never affects public schools, to be sure ... /sarcasm off). If vouchers are bad because they don't really produce any improvement ... Meh. They produce dislocations and there's an argument to be made for teachers as workers, esp. teachers as union members. There's also an argument to be made for dealing with SpEd and other special needs students, but part of that is specious and part of it is due to perennial and egregious Congressional underfunding of Congressional mandates.
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