This boot was built well and it was light but it ran small and narrow. I went up a half size and they still didn't work. The free return credit took over a month to process once they received the boot. So if your looking to try several pair, you may not have your refund for a long time.
Had a bad accident which left me with a fused slower spine and unable to get my Vortices on and off without imitating a pretzel for half an hour. Not as tough as the Vortices I had to sell, but better than my ST Airs, if not as all-day comfortable.
Main difference for me is that I can get them on and off as I'm hoping to return to the track next year.
I've worn Sidis for the past 8 years and it will take a lot to get me to change. Will probably get another pair of these as the main downside is they don't have replaceable lowers.
Similar comments to what Scott wrote: I got these in the same size as my running shoes (about 1/2 size over dress shoes) and the boots never felt really comfortable. They're just too tight to the point of hurting. Thinking it's a matter of breaking-in, I started riding in the Sidi's, but they never become comfortable enough. I just ended up ordering a 2nd pair a full size larger and hope that these will fit as expected. Will make someone else happy with the barely worn smaller pair.