If you're mostly listening to jazz then you don't have anything to worry about. There's not a lot outside of artificial sounds or natural sounds that get that low.
And yes, sealed boxes are great for a thin, accurate boom but without a port the eq curve starts dropping decibels at an unacceptably high level (for the things mentioned above). Again though, this might e fine depending on your music listening.
This is why you'll always see ported boxes on home audio systems sub woofers. That's how you get the low rumbles in movies or low bass that shakes a trunk at loud levels. It's a more accurate representation of the entire humanly audible sound range.
Now, if you wanted the mix of tight bass in a sealed box with good sub bass representation, you'd need a MASSIVE woofer. Its simply physics, not something we do because punks need to shake their cars. This also goes back to an 8" woofer vs a 12" one. When you start getting as small as an 8, those lowest frequencies are hard to push even with a ported box.
This is not accurate, but for the sake of not needing to find a sub's eq curve in a sealed vs ported, check out this image:
Google Image Result for http://i.imgbox.com/hOGI6D7g.jpg
Pretend red is sealed and blue is ported using the same sub. What many people would say is that the red is nice and flat, not boomy, and goes low enough (in reality, red would go a little farther to the left before dropping the curve). If you look at the blue one, it rises up and must be boomy like those kid's cars!! In reality, it accurately plays flat to our ears due to the human sound curves I linked above. That, and it plays LOW which I personally love
feeling. Quite a different experience than other frequencies, which is why movies sound cool and impressive.
So effectively, that blue bump is required for bass to not sound nearly non existant to our ears. The model 3's sub is like the red line.