There are many models of full face masks out there and in general all are good. I have used the AGA Divator a fair bit in commercial diving and own one. Great mask and as one other who dived in contaminated water you can get it with positive pressure inside to prevent ingress of contaminated water. I dont believe you will be doing any of that nasty diving.
For me I have dived in water below zero Celsius and with a straight forward DV/Regulator. The pain of the cold goes away quick. If you are worried still and want to get a full face, then beware they are costly. A good hood is a must and more often than not a trick is to wear hood inside out and the full face seals better against the hood then. If the hood is a good fit then there is no problem fitting the hood over the mask seal as when your body heats the film of water inside the hood you will remain warm. Hope this little info helps