The 512 is going through the same problems that the 510 did. There are really big gaps on the line. Usually, there's one or two CLRVs trailing behind a Flexity. For example, yesterday around the evening, there was no streetcars west of Oakwood Avenue. A CLRV at Oakwood heading eastbound was in front of a Flexity (4420) which was at Oakwood heading westbound. Therefore leaving a 30-minute gap. Trailing behind that Flexity (4420) were two CLRVs. One of them short turned at Lansdowne to fill the big gap.
Today, there are 5-6 Flexities on 512. The service is better however streetcars now tend to bunch up near St. Clair West Station now that they changed where they load and unload passengers. After 3 days, people are still confused. They had signage posted everywhere in the terminal for weeks about the change. Even a TTC supervisor said that they needed better signage. They also have to fix the announcements for Winona and Spadina as they are pronounced wrong.
So far, I think it's a fail as there are so many big gaps on the line, streetcars bunching up especially around St. Clair West Station, no fare machines along the line, running Flexities with broken machines, and problems with a few island stops as the Flexity stops with the back door blocked by a garbage bin.
It's nice to have them on the 512, but it was fine when the route was all CLRVs. I think they should run the Flexities on the weekdays and weekend and holiday service should remain all CLRVs but I highly doubt that they would do that. I gotta say though. If you wanna ride a Flexity going fast, ride the 512. Every Flexity driver that I had so far on the 512 drives fast during the late evening.