Yes ifleeplanes, in my previous post I was concentrating on the standard 2NM of lead, rather than the actual radius of turn of an aircraft. I know the radius of turn of the aircraft I fly, in various speed configurations, and can therefore pro-rate the degrees of difference between the lead radial and the required track, so that I turn at the radial that equates to my radius of turn, whether that's before or after the lead radial shown on the chart.
It has to be said though that if we assume that TAS = GS for a given set of conditions that equates to a GS of 180 knots, the radius of turn for 15 degrees of bank is 1.8 NM. At 20 degrees of bank, it's 1.3 NM and at 25 degrees, which I mostly use, it's 1.01 NM. These differences will certainly make a difference to the lead radial that would actually be used. Note that they are all less than the 2 NM lead provided on the chart.