There is absolutely no way a short rod can roll cast any where near as well and as far as a long rod. Not even close!! Why do you think most spey rods are 14+ feet long??? All a sepy cast is, is a modified roll cast. Rich, your formula make no sense, you can only roll cast 4x the lenght of your rod??? Are you kidding??? A 14' spey rod will roll cast well over 100 feet and even out to 150 feet. (yes thats more the 10 times it's lenght). Secondly, there is no question that DT lines roll cast better. The DT lines have a belly that is all the same mass & diameter, the running line on a WF line like a Wulff TT is to thin to transmit the energy to the fat head of the line.