But what about Madaras fireballs that managed to get PUNCHED away, therefore the fire must have had some kind of force behind itThroughout the manga it has been shown that enton lacks stopping power. Enton lacks the cutting power of wind or even lightning.
An example of this is naruto and sasuke's final clash. The enton did nothing to enhance sasuke's chidori, infact it ended up doing more bad than good. It was also easily deflected by an ordinary rasengan.
What I am trying to say is you can't assume that the enton arrow will have the same cutting potential and stopping power as indra's arrow. If the arrow gets enhanced by the flames it will lose form and it will not consume the rasengan let alone the TSB.
In short the enton arrow would be a worse choice than the lightning one.