I've been going with a size 10 Vapor 9.5 for my last 4 purchases. I'll be sticking with a size 10 with my first Flyknit that I just bought. I can't resist... I wanted to try the Air Zoom Ultra, so bought one a few months ago and also went with a size 10, which seems perfect.
I just make sure to lace them up tightly enough. My second toe has always been my main concern. When I started playing 3 years ago, I played with a Wilson brand that was too tight, and that caused issues with my nail on that toe that took a long time to heal once I switched to Nike size 10.
I'll post back in a week or 2 once I've been able to play at least twice with the Flyknits. Mind you in won't be on a real hard court, but a more rubber like substance used to play indoor in the winter months.
The Flyknits are just too cool looking. I'd get them all, but the price is too much. I play 3 times per week, but rotate my shoes. I'd hope to get at least 6 months out of them.
I still wear my first Vapor 9.5 which I bought in November 2015. They are good on that indoor winter (rubbery) surface, but might be too worn now for a real hard court (and I don't think trying to slide/glide in my 40s is a good idea). I've just started to notice the material on those shoes start to slightly tear though, so I really don't expect them to last much longer.
