I'd go for 12l long. Dumpy ones are fine but some BCs with two straps won't hold them. Like mine for instance. 
__________________ "I feel unusual.." Withnail and I "A lot of people attack the sea. I make love to it." Jaques Yves Cousteau "The sea once it casts its spell, holds one in its net of wonder forever." Jaques Yves Cousteau |