Boka / Bokabob 1.5" vs. 2" columns width and speed data?

[montanadave]

I've done hours of (really fun) research reading here and on yahoo about the Bokabob / Bokakob / Boka dual slant plate design. I've read through pages of design modifications and discussion about every adjustable aspect.

But, in all my research, I haven't found much about the actual difference in column diameter. It is clear that a wider column will produce "faster", but there is limited (if any) empirical data that shows just how much faster. I'd guess that a 1.5" column (with a cross section of 7.07 sq.in.) would have roughly half the production speed as a 2" column (with a cross section of 12.56 sq.in.)

Does anyone have any experience with the columns they could share to help those deciding between the 1.5" and 2"? The 2" is double the cost and harder to find, and for a smaller personal Boka, that might be acceptable. But, some say the 1.5" is painfully slow. Can anyone share their numbers? (Also, please let me know your BTU too to best compare apples to apples.)

Thanks!