A double batch doesn't take any longer (other than a bit for heating up
60L rather than 30L...but we are talking 30 mins over a brew day).
What will you be brewing on (heat source)?
My 80L fits nicely onto the 4 ring gas burner, amd I like the fact that I
don't have to worry about boilovers etc. And if I want to do a double brew I can.
Mind you, 60L on the stove might be a bit of a worry for the stove rack.
I would be happy to say go with 50 or 60l, but 40.......