As a experiment I converted a little sealed practice combo, an Ibanez soundwave. To ported with the help of winisd and a new speaker. That was a few years ago.
Beforehand I felt the combo had a great neutral sound, which in my opinion, was the best I had heard in an inexpensive combo. Great for jazz. It just lacked any real authority. I also liked the fact it didn't rattle or have any funny resonance.
I can't remember all the details but after porting, and the new speaker. It sounded not that different in its basic sound signature. Apart from it had better low end and the volume was maybe very slightly increased. There was limitations to the small box as to what I could actually achieve.
Many bass and guitar players have plugged into the little combo and said how good it sounds. It's far better than my previous practice amp a fender rumble v3 1x12 100, not that was just boomy and also rattled badly.
On another note. It's funny how in the early days some bass cabs were open backed. Just sealing them surely would of made a big difference.