What I noticed was the engine seemed more responsive, probably because it was no longer choking on the hot oily air and getting a cool , clean intake charge.
I went with the vent filter. Not as sexy as a catch can, but much easier to clean.
I'm afraid it will void your warranty. Mainly because Harley made a deal with the EPA to choke their engines and they won't like you undoing it.
If you only have the factory one year warranty I would get started , because how likely are you have a major failure in the first year?