david graham wrote an answer about La Sportiva Solution Vibram XS Grip2 Climbing Shoe on June 9, 2014
The great thing about La Sportiva is if you're a 44 in 1 pair your pretty much a 44 in all the other shoes. That being sad you may want to go down a half size as your performance fit. I have the mythos and the solutions as well. the mythos was my first shoe (back when i didn't know better or think about stretch) and I got a 44.5. I now own the solutions in a 43.5 which is tight but not crazy tight like some people get. Basically in La Sportiva i go 43.5 for performance, and 44 for comfort. if you really did get the mythos pretty tight i would call 38.5 your performance size (even though they stretched, god how they stretch). these guys don't really stretch though so if you want a tight bouldering shoe i would say go with these in a 38.5, if you're more in to comfort you might try out the 39. With backcountrys' return policy you have some room for error, that's the great thing about this site even if it isn't the cheapest, you get what you pay for in service and quality control.