My 2c is that you can never be "too cautious" Bundy. Good for you.
Tell the guys behind you why you are waiting and let them go ahead of you if they want to. I agree with you that in still air the turbulence will hang around from the point of rotation, from the departing aircraft, for longer. a slight crosswind will move it out of your path qiuckly.
I have not experienced it on the ground yet but have felt the bump after flying past behind and below other machines. My wife and I were given a real scare at New Tempe once. We were taking off on 28 when a dust devil approached from the right, directly next to the runway and it was moving into our take-off path. I was committed and could never stop before getting into it. Fortunately I could see it! When we hit it I was expecting all hell to break loose - and it did. Another fortunate thing is that generally dust devils are thermals and therefore take you away from the ground rather than the other way round. It was an ugly take-off but we were soon through it and everything returned to normal. I suspect if the whirlwind cannot be seen it could easily cause an accident on take-off or landing.
This picture shows wake turbulence vortices behind a landing airbus.
I too am a little lighter than the guys I generally fly with so I get in the air before their point of rotation if I can.
Good topic Bundy, allways worth considering.