If you're going to use the weapon to shoot without a light of any sort & rely on your night vision, forget about ported bbls and almost all the magnums. Even if there is no muzzle flash out the bbl, the flash at the cylander gap is blinding enough.
OTOH, if you're going to use a light to aid your shooting, ports are not going to hinder your performance. For example, when things go "bump" in the night, and my wife pokes me in the ribs to check it out, I take whatever pistol or revolver I keep in the nightstang along with a quality light. I use the "top-of-hand pressed to top-of-hand" technique (can't recall the actual name).
I am not about to shoot at anything I have not positively ID'd while in the house, so that means a flash goes with me or the gun stays behind, too. Same goes for ANY room clearing activities anywhere.
After doing this for a while, I came to the conclusion that tritium night sights are not all that useful in most light-reduced situations. At these short ranges, with a decent light a flash image of the front sight post is all you need, if that. One of those fiber-optic front sights might be just what the Dr. ordered.