I'll start by saying I wasn't a huge fan of the T6 racers, in fact, I had to return them. The heel collar dug into the back of my heel and rubbed them raw after like three days, but everyone else loved them, so I figured I'd try the T7s. The first update you'll notice is the asymmetrical upper. Personally, I didn't mind it that much, although I didn't find it all that beneficial either. It didn't make my feet feel more snug or secure, but it wasn't overly annoying either. At first the toe box felt like it was bigger than the T6s, which was kind of a hindrance for the first couple runs, but then that feeling went away, so it might have just been me being weird.
Now for the thing I was really concerned about- the heel collar. Really not a problem at all. Its shaped different- its more rounded- than the T6, so that might have done it.
|Heel collar heights- T6 (left) and T7 (right)|