The consideration is to think upon the point at which the two techniques would put you at the same speed with TO thrust set. If you are heavy, then the rolling start with a prompt spool up and acceleration is going to put you ahead. If you are light, then you could loss quite some difference in length unless the rolling acceleration is made to be very prompt. So far as spool up on a normal intersection, going to 40% with 90° to go is counterproductive - uncomfortable, tyre scrub wear, etc. What you do, in practice, is taxy at a normal speed and, while the aircraft is turning towards the runway heading, spool up and, by the time you are near aligned, you are accelerating fairly quickly.
The critical consideration is the promptness with which you get the thing going. Should you spool up slowly, take all day to accelerate gently and slowly to TO thrust conditions, then you could put yourself in an awkward position on a short runway. Providing you are prompt and decisive, it works real fine.
putting the brake on and going to 70% before commencing the roll is probably beating any rolling start.
.. and great for FOD unless you are on a nice clean runway surface.....