As near as I can tell the sole advantage to extended ported chokes to shooters is they provide a good place to hook in the can opener on your Swiss Army tool for loosening or tightening.
The advantage they provide to the makers is they sell big time, providing jobs and stimulating the economy.
I doubt I could tell the difference in kick between ported and unported chokes. By the time the main gas pulse hits the holes, the shotgun is already recoiling.
As for your bud's 870, a longer forcing cone is called for BEFORE buying any more choke tubes. A longer cone(within limits) MIMICS a tighter choke, but it's just denser because there's fewer flyers. More pellets stay in the pattern.
If I were setting up a card gun, the cone is where I'd start tweaking.