D. Schonbrun

They won't go down to -25C. I would say -18C is the min temp rating for these without overboots. If you need -25C, look to the Scarpa 6000 Guides, or a plastic boot like the Omegas.

I would say the 44 or 44.5 to avoid toe bang. Try both on with a pair of custom insoles and go kick practice kicking in the store. You'll know which one is better for you based on how many toe kicks it takes before you feel the front of the boot.

If you're moving consistently... probably around 5-7F. If static, around 15F. If you want this for all around use (as many of us do), use a GTX gaiter which will add warmth to the lower leg, and make sure you have good circulation in the boot. Finding the right combination of lace tension, socks, and insoles is key to happy feet.

The Scarpas are a bit wider in the forefoot and the toe box. I have wide feet (E width) and am very pleased in the Jorasses Pro's.

Half or Full size up from your street shoe is good to avoid toe bang. If you go a full size up, you may need to take up a bit of volume so that your foot doesn't slide forward.

The Scarpa Model that compares to the Nepal is the Mont Blanc, it's a full leather exterior. Scarpa's vs. Sportiva's typically come down to fit. Try both on and see.

It Depends on the temp. The Freney's don't have a removable liner. As with all boots of this type, it may be challenging to dry them at night whilst in a tent. If you are bunking in a structure and have heating, then you're fine. If not, I might go with a boot that has a removable liner which you can place in your bag at night to dry it out and warm it up.

I have a wide foot and the Scarpa's work for me, you should try on a pair as they are noticably wider than Sportivas. The weights you are citing are different, in that one is for a pair of boots, the other is for a single. The two boots weight almost the same... within 4 oz.

For a 7,000m peak, you cannot wear a Leather boot like the Nepal's. You need a plastic shell, with a separable liner, and an overboot/gaiter. The least warm boot I would even consider for that altitude would be the Scarpa 6000 guide. Boots for 8,000m would be advisable... Sportiva Olympus Mons, Millet Everest, Scarpa 8000, Kayland 8001

Avg Temp on Vinson is about -20F during summer and the Massif tops out at 4,900m. I don't think this boot is overkill, but if you're not going to go to 8,000m peaks regularly, you could go with a plastic 2 layer boot and add an overboot. That would give you more flexibility... The Millet's are great, but very warm for most applications below 6,000m.

BD's harnesses are UIAA and CEN certified... check with the race officials, but it's likely more than adequate. That said, you will need a bosun's chair attachment for longer work sessions. The leg straps won't be very comfortable to sit in for more than a few minutes.

It depends on the boots you're wearing. Most people climb Rainier in boots that are step in crampon compatible (groove on toe and heel). The Sabretooth do come in a step in version (which I have). They should work well for you on Rainier.