 Re: Octopus recommendations
Most brands have specially designed regulators for cold water. The Arctic from Aqualung has a very good reputation.
Scubapro also has good regs for cold water and environment isolation kits.
Keep in mind your behavior is much more important than the regulator you use. The best regulator will freeze if you don't care the way you use your air.
For example don't inflate your dry suit or BC in the moment you inhale. You use air only on one device at a time to reduce the quantity of air delivered through your first stage. Of course you use 2 first stages and connect the hose logically, so that if your 1st first stage freezes you or your body can close it and you can swap to you octopus connected to your 2nd first stage.
If this technique is not familiar to you take a specialty course with an experienced Instructor for these conditions of water.
I hope this advice could help, don't hesitate to ask should you need more details.
Mako | 
Linear Mode
