I've searched this forum for Posts from people who fitted the Renthal Low bars and their feedback on whether any of the switch gear or brake lines had to be changed. I actually found nothing!
Many have fitted the Ultra Lows and not needed to change anything else (including myself).
You can angle the bars more back or forward (in the Risers), which can help reach/posture/cable reach etc?
Another option even change the Risers along with the Bars, to get the best combination.