>Michael, you say you do not. Would you mind expounding why?
40 years of experimentation... and as Challenger points out, nectar varies greatly and bees are quite willing to work anything from 1:2 to 2:1 as a source and in my experience will draw comb the same in that wide range of concentrations. Some people, however, are convinced, based on their experience, that bees draw comb better at 1:1 than 2:1. Everyone is entitled to their own experience and conclusions.
My conclusion is that comb production varies greatly depending on a number of factors including ambient temperatures, nectar availability, amount of empty comb, age of bees, and momentum of comb drawing. Heat helps them work wax. As bees produce wax they get more efficient at producing wax. As they construct comb they get more efficient at constructing comb. I think any difference in comb drawing is due to one of these as opposed to the concentration of the nectar/syrup. If anything, it's less work for the bees if the sugar source is more concentrated. But mostly I make it more concentrated because it keeps better. Syrup spoils quickly when you get down near 1:1. It lasts much better at 2:1 but is difficult to dissolve, so I end up with 5:3.