I'm new to winter mountaineering. I have summer packs that I like, but, they are too small for my winter gear(48l). I'm looking at something in the 60-70 liter range that can comfortably carry 50 lbs. I'll be using this for winter only and plan to do 2-3 day trips. On my radar is the Cilogear 70l, Black Diamond Mission 75, Lowe Alpine Metanoia 65, Mountain Hardwear S-Col 70. Any other suggestions are welcome. Who has firsthand experience with these packs?

I'll try to give some input as I've used most of the packs you're mentioning:

I have a Cilogear Worksack 30L and can attest to CG's quality and the company's good service/support. I didn't know they had a 70L--do you mean the 60L or the 75L Worksack? In any case, their smaller packs use foam pads and I'm not sure how robust the suspension is in the larger ones (the webpage mentions upgrades, it's hard to understand what they mean without trying the pack), so they may be insufficient if you plan to carry 50 lbs for extended distances. Regardless, if you are okay with the foam pad support, I would recommend a ColdColdWorld Chernobyl 50L. It is my go-to pack for every time I need something more than a 25-30L daypack.

When I need to carry big loads to a basecamp or something, I use my BD Mission 75L. Comfortable, simple design, and generally well made. There are a few design things that I'm not sure I love, but overall it's a good hauling pack with no frills. I've used it with probably up to 60 lbs for 12-15km. Not the best hiking scenario, but no back pain or the like. Shoulder straps could be padded better.

I've used the MH South Col 70L as a rental pack on certain trips in the Cascades and was happy with it. But those instances were a few years ago so I don't remember the details but I do remember that it was comfortable enough that I didn't complain or constantly fiddle with adjustment. In those cases I carried loads from 35 lbs to probably around 50 lbs for a day's hike to some kind of camp and then back out. Compared to the BD, I like that the current BD Mission has a crampon pocket on the outside.

In summary, all your options are good (I can't speak to Lowe, though) and so you really can't go wrong. As noted, CCW is my favorite pack and the one I use whenever I can. Construction is great, pack is very durable, and it is just plain comfortable. That is what I recommend, even though it wasn't on your list. That said, if you expect to regularly haul 50 lbs for extended periods, you probably want to consider one of the larger ones with a full suspension.

I have the MH South Col 70. Mine is the newer model which has the "Outdry" waterproof feature, versus the older model which is not waterproof. The older model had all kinds of gear loops on it of questionable utility, the newer model does not. I really like this pack. It is comfortable even with 55 lbs of gear in it, has a highly useful crampon pouch and a very useful zippered compartment behind that. The top compartment can be removed and reattached in seconds. The hip belt has very useful gear loops which can also be used to holster an ice axe temporarily. The side compression straps and the pockets on the sides can be used to hold snowshoes to the sides of the pack, or oxygen bottles, or whatever to the pack. The pack is light enough to be used for a summit attempt but big enough to haul loads with.

Since you want to carry 50 lbs comfortably, I will echo IJD's suggestion and get a pack with some type of back support. I have used packs from all of the manufacturers you mentioned, but not the specific models. Generally, I found everything I have owned (including 2 packs) form Mountain Hardwear to be pieces of shit. I find CiloGear packs to be too fiddly, overly complicated and fragile, but they do carry and climb very nicely. I really liked both Black Diamond packs I've owned (BD Ice 45L and BD Shadow 45L). I found BD packs to be a good balance of weight vs. durability and function vs. simplicity and carrying ability vs. climbing performance as well as a good value . I generally like Lowe Alpine (I've owned four Lowe packs).

In addition to the ones you mentioned, look at CRUX AX 70 and AK 70. If don't mind spending 2 - 3 times more, then take a look at McHale packs http://www.mchalepacks.com/ultralight/D ... 20page.htm. I have a SARC that Dan McHale built for me with lighter materials and a smaller hip belt. That was in 1997 and it has since been dragged all over North America including several Alaskan trips. I am certain it will easily last another 20 years.