In reply to purplemonkeyelephant:
Yes. I guided an 1,100km ski trip to the South Pole and did about 70% of it in just a pair of Windstopper gloves. I only used insulated mitts for the last 100-150km or so. Such trips now also often use (at least for clients) a neoprene hand-guard, mitt type of thing attached to the top of the pole, called 'pongos' that are actually quite good when you get used to them.
The problem with modular systems is sizing the individual layers to fit well and not restrict circulation nor compress insulation. I also find more than two layers ruins dexterity.
I have various insulated mitts but the ones I go to most are older model Marmot Primaloft expedition mitts. They're light, flexible, don't get compromised by sweat and a rip doesn't render them useless. I think the current version has a leather like palm which I'd be concerned about.
The old Rab expedition mitts were ridiculous, but the new ones look pretty good. Gloves are very individual things and are best tried on in person.