Faster projectile speeds would mean a flatter trajectory and a lower draw weight would enable steadier holding over targets as well as less fatigue over long sessions. On top of that, a tapered bandset has a predictably safe breaking point we'd learn to trust so we'd never flinch in anticipation of a break. I don't think any of that would be detrimental to shooting form?
There are pros and cons with tapered vs straight cut bandsets and if you search, you'll find a lot written on the subject. I wouldn't worry about it affecting "accuracy". Accuracy depends on a lot of other things. Everytime we make a small change there will be a change in our shooting performance owing to familiarity of equipment regardless...
Just experiment, learn and enjoy... we all have preferences discovered through an adventure of experimentation. Have fun!