Very very nice set-up. Just wondering, have you tried having a mini carabiner on your coat cuffs that you can attach the mittens to? I have a jacket that came with tiny webbing loops on the back of the cuff for this purpose, but if your jacket has a thumbhole sort of cuff, those can also serve to attach the carabiner to. This way, you are less likely to tangle yourself than with cordage going up one sleeve and down the other, you can unclip the mitts completely if you want to stash them away, and you avoid another set of straps around your neck/shoulders (this area seems to accumulate more than it's fair share of straps and slings).
I like your idea of separate cold weather 'work gloves'. Gives your other mitts a chance to air and dry out, and possibly saves them from abuse. I have worn goretex lined leather gloves before for active use when it's cold, and whilst they kept my hands toasty warm whilst moving, once you stop and they are wet with sweat they are not great. Are those German mitts a goretex type material or a more breathable type? I guess you're looking at cold dry conditions.
Anyway, whatever arrangement people come to I think the thing to do in seriously cold conditions is to also carry spare mitts (Dachsteiner's, thick compressed wool are good) in the pack in a waterproof bag as a back-up in case your hands get dangerously cold and wet. Even the best mitts can get soaked easily and that can be a real peril in the cold, most people will carry spare socks say, but many won't consider more mitts. I guess your work gloves could kinda pull double duty for that for you too (or perhaps a spare pair of felt liners for your 'normal' mitts). Bear in mind though, if you are digging snowholes your gloves WILL get sodden! Best have something that keeps you warm even when wet for your backup mitts, for this particular purpose I think heavy wool is king, the less processed and more oily, hairy, coarse and itchy the fibres the better! Also, consider 'dressing down' for snowhole building. If you can get away with only getting your contact gloves soaked and then having your insulated mitts still dry to get back into, that's obviously a lot preferable to getting everything soaked.
Another thing is space - my everyday wool mittens are homemade and pretty spacious and overall it's a good thing. Often it annoys me when I am trying to do something finnicky, but it also allows me to pull in my thumb and roll my hand into a fist/ball when cold to get that bit more warmth. It also means I can put a thinner pair of wool mittens on underneath them to layer up, without them getting too compressed and chilly. And just, the more hot air trapped inside, the better.
Best of luck with the winter course and I hope you get some good cold temperatures over there!
