There are plenty of reasons you may want to install a custom Rom to your device. Themes, custom features, and even performance enhancements like debloating and system tweaks are all great reasons to install a Rom. The one major downside to installing roms is the fact that you normally lose stock functionality. Early Note 4 ASOP roms were great, but being that they removed the S-Pen features they were not well received.
One of the greatest features of the OnePlus3 is Dash Charging. Dash Charge is not like Qualcomm quick charge or Samsung's Fast Charge. Dash Charging continues to quickly charge your phone even as you use it without causing your phone to overheat. The OnePlus 3 is one of the most dev friendly devices and as such roms came early, but unfortunately early roms removed support for Dash Charge.
We finally have a pretty decent list of roms which support the feature. Roms include Resurrection Remix, FreedomOS, PureCM, XOSP, HydrogenOS. Links to the above roms can be found below.
Resurrection Remix
FreedomOS
PureCM
XOSP
HydrogenOS