I went back to 3 fletch last year, but am back to 4 fletch this season.
I've done 4"x4 but will be using 5"X4 low profiles from here on out ...until I change my mind again.
Recent experiments have me excited about 5X4 and also the 60X120 pattern seems to work good out of my longbow, but I have to re-orient nocks after fletching to avoid having to raise the nock point.
I would suggest experimenting a bit with aluminums or carbons with a uni style nock to see what your bow likes.
I'm also into symmetry and just wasn't comfortable with that odd colored feather on my shafts
The performance loss in extra feathers is made up for in my opinion.
If I had a vario clipper, I'm thinking 4.5" would be about perfect for broadhead use and 3D.