Are you saying you favor Getz's tone, or he's just one example? Henderson and Lovano certainly play with a dark tone as well. And, you're still looking to project in a jazz setting?
With the right mpc/reed combination, you might even try a legit mouthpiece like a selmer E. In addition to the suggestions above, Saxscape also has an Xtra Dark with no baffle. You can hear a sample on Ken's site, of course your mileage may vary. Certainly, there's a lot of positive feedback on here about the Drake and Phil-Tone although I'd consider buying a rubber Link as well (was very close to picking one of those up myself, when I opted for my FatCat proto).
Reed choice does make a lot of difference though. Start using a traditional (non jazz) cut with the same strength or maybe 1/2 harder (you may have to adjust a bit then), and you'll darken up on whatever you're using.
Good luck on your quest!