They're both risk factors. Imo, you need to have a fit team with 99% good for attacking and defending. You will lose condition faster using this so if your opponent makes subs they might be fresher than your team.

Hard tackling gives you more tackles meaning less chances for opponent and more possession but you run the risk of giving away set pieces and bookings.
I gave away a penalty because my ass man advised me to use it. Went from 1-0 up to 1-3 down