Scarpa (Vapor V) to La Sportiva (Miura) sizing

Anyone have experience with Scarpa > La Sportiva sizing? Specifically Vapor V and Miura (Lace), I'm currently wearing a 40.5 for Vapor V but the toe box is really tight for some sessions. I read some mention to downsize 3 EU sizes for Sportiva, but my street size is 39, and some mention to downsize for scarpas as well I also have a pair of Evolv Kira is 39 that fits well. Was planning on getting my vapor v resoled soon and possibly stretching it half a size.

All the stores in my area don't have the shoe in stock or a comparable shoe in my size. Going to buy the Miura in 2-3 sizes online to see which fits best, but I don't know which direction to go in. 

I probably measure somewhere between 42-42.5 on a brannock. I wear 40.5 in Scarpa and 39 in La Sportiva for a tight 'performance' fit. 

Everyone's feet are different, as is their tolerance for downsizing. As a rule of thumb though, La Spo runs significantly larger for a given size than most other brands, Evolv tends to be truer to street shoe sizing, and Scarpa is somewhere in between. The fact that you upsize your Scarpas by 1.5 sizes and are even considering having them stretched, while being happy with your evolvs matched to your street shoe sizing is surprising.

Similar to the poster above me, I size my Scarpas at street shoe minus 1.5-2, and my La Sportivas at street minus 3-3.5. Evolv is true to street shoe or perhaps a half size down for me, though truth be told, I've never gotten on well with Evolv, so that's just based on try-ons. I've never actually owned or climbed in any of their shoes. That's all for an aggressive performance fit, as per my preference.

I'll guess based on your Scarpa sizing that you don't want to aggressizely downsize, but even so, I'd think you'd want to come in below your street shoe sizing for the Miuras. I bet if you order three sizes from 37.5 to 38.5 that you'll find your shoe. 

FWIW, I wear Miuras in my street shoe size with no bagginess in the heel and a slight curl in my toes. I wouldn't even be able to get my feet into them if I sized down ~1, let alone 3.5. 

Got me thinking about how my shoes actually fit etc. And upon further inspection I guess my street size ranges from 39-40 (whatever US women's 8.5 is). The whole thing is just so odd since the sizing of Evolv/Scarpa seems so inconsistent in regards with my foot. 

I was thinking maybe the vapor v currently has a tiny bit of dead space in the heel (like the bottom corner). I always thought it was kind of normal/expected since the toe box feels unbearable some days at least in the beginning of the session.

A size 39 Scarpa Vapor V is going to be approximately the same as a 38 La Sportiva Miura V. The Miura Lace is going to be more narrow which can effect the way it fits, but length for length it is the same. 38 +/- 0.5 should get you there.