I had the Sidi Crossfire 2s but found the boot way too narrow. My foot just cramped up after an hour on the bike.
I just got a pair of the new Alpinestars Tech 7s. To be honest, the build quality, the buckle system, ankle mobility, and the liner all seem as good on the Tech 7s as they are on the Crossfires. (The old tech 7s had the crappy buckle system, but the new ones are almost exactly the same as the Sidi system.)
One thing that I will make extremely clear, the customer support I received from Sidi was despicable. My soles wore out within three rides so I tried to warranty the boots. They refused but suggested I buy the replacement sole for $50. Reluctantly, I agreed. That was in May. I to order the soles again in June, and again in July. I gave up in Aug.
In September, I bought the Tech 7s. The sole also has begun to wear. The company offered to replace the sole at no charge. I also ordered a second pair of replacement soles, which came in three days later.
Sidi = $849
Alpinestars Tech 7 = $385
Don't be a sucker. The Sidi are all hype.