Jonathan,

Your approach is a good one and there is not an entirely clear answer. I think it really depends on the glider you're flying and your given situation. There are a couple things at play.

1) Time in lift/sink
2) Dynamic Soaring effect (from the pull-up)
3) Tactical considerations

So for the simple speed-to-fly indicator, it is telling you the optimal mathematical speed to maximize time in rising air. It does NOT assume the drag from a rapid pull-up. It is near to impossible to chase the needle and to do so would be inefficient in its own right. However, maximizing time in lift relative to sink is certainly a good thing and it makes sense to slow down in the good air or thermal. The question is how much. If you are in a relatively big area of lift and you can gradually pull up (1.5-2g max), then following the STF could make sense.)

Now, in some gliders you can pop off the air (dynamic soaring). This particularly works well with light wing-loaded gliders and/or gliders that have low induced drag and airfoils that are not prone to separation. In these gliders, dolphin flying carries a different meaning as you are extracting energy by the very act of pulling against the gust or thermal. The STF is irrelevant in these cases.

Some examples of gliders I had flown-

1) Schweizer 1-26E-

Great dolphining machine! The stiff wings and the very light wing loading let you pop off the gusts really well. The strategy for dolphining, especially into the wind is to slow down to minimum sink, sometimes even to minimum controllable airspeed and milk out the air as much as possible. The goal is to avoid turning at all costs. There is a huge amount of energy gained from dolphining/dynamic soaring off the vertical gusts. On a convective day in the East, it is possible to consistently achieve 25-1 glides by doing this.

2) LS-4

Mediocre dolphining glider. No flaps, so lots of drag on pulls. Much better to smoothly slow down to best glide, possibly to minimum sink if the thermal is quite big.

3) Standard Cirrus-

Awful dolphining machine. Huge airflow separation when changing angle of attack. But really great performance in club class just flying straight and smooth!

4) Duckhawk-

Unbelievably awesome dolphining sailplane. Auto-flaps, so perfect AoA on pull-ups, low induced drag, low separation make it conserve most of the energy on big deviations. Makes a lot of sense to pull hard and often.

(Listen to Bill Thar's speech at convention about Auto-flaps to learn more)

The tactical consideration is relevant in that there are two types of dolphin-flying. There is dolphining to get more altitude, and for greater speed, both which have a different technique. When dolphining for more altitude, I will cruise slower, pull more aggressively and slow down to minimum sink. When dolphining for "speed", I do gentle vertical deviations, less draggy, but to spend a bit more time in the lift compared to sink.

In practice, here are two scenarios-

1) You are going upwind and you have found a thermal street. You are climbing, drifting downwind. The question is when do you leave? You can leave earlier, slowly float up in the street by wafting up, or you can leave later and then blast along cloudbase. Generally I find it more efficient to leave earlier and waft up.

2) You are on final glide low. You need to make up 1000ft. Then dolphin more aggressively and pull out every bit of altitude. Once final glide is made, then speed up and don't deviate vertically as substantially.

Hope these thoughts were of interest.

Best Regards,
Daniel