As for sizing on the Millet Everest Boots, for foot sizes smaller than a US 9.5, we recommend that you purchase boots 1 size larger than your normal shoe size due to swelling of the foot at high altitudes. So, if you wear a size 9 US, we would actually recommend that you purchase a 10 US in the Millet Everest Boots. For foot sizes of US 9.5 and larger, we recommend that you purchase boots 1.5 sizes larger than your normal shoe size (i.e. if you wear a US 10, you would purchase a US 11.5).

AAI DENALI EQUIPMENT CHECKLIST

High Altitude/Cold Weather Mountaineering Boots:Double boots are required. They should be designed for extended use intemperatures at least as cold as -40F. Modern synthetic integrated boots (those witha built in overboot/gaiter) are suitable for this climb. For traditional plastic boots,thermo-mold liners are warmer, lighter, and more comfortable than standard liners. If you have heat-moldable liners in your boots already and you have worn them forseveral trips, you may want to have them re-fit to ensure that the foam has notcompressed and the temperature rating has been retained.
Shell Materials: Synthetic, plasticLiner: Thermo-moldable or High Altitude models Examples Include: Kayland 8001, La Sportiva Olympus Mons, Lowa CivettaExtreme, Scarpa Phantom 8000 and Inverno, and Millet Everest.

they look a lil too inflexible and bulky like u said

I would not think so, Denali is normally colder then Everest anyway.

As for sizing on the Everest Boots, for foot sizes smaller than a US 9.5, we recommend that you purchase boots 1 size larger than your normal shoe size due to swelling of the foot at high altitudes. So, if you wear a size 9 US, we would actually recommend that you purchase a 10 US in the Everest Boots. For foot sizes of US 9.5 and larger, we recommend that you purchase boots 1.5 sizes larger than your normal shoe size (i.e. if you wear a US 10, you would purchase a US 11.5).

These are posted in US Mens sizes.