I have a Rythmik E15HP and an SVS SB-12plus (which I think can fairly me called the precursor to the SB-2000).
For tight and musical, you really want the Rythmik if you can afford it. The E15HP offers extension and output over the F12, but I believe the tightness is equivalent among all of Rythmik's
sealed designs.
I would also chose the PSA over the SVS based on measurements. It may actually equal the Rythmik, but without hearing it, I am reluctant to recommend it over the Rythmik.
Here are some pulse response measurements taken by Jim Wilson that I find useful for evaluating how tight a sub is.
Here is the Rythmik E15HP (which is very close to ideal, as the signal drops quickly and evenly):
Here is the SVS SB-13Ultra (which is SVS's best sealed sub). Notice how the sound is still at 80dB after 20milliseconds. This is very good performance, but the Rythmik did it in under 10ms. Also you can see the imbalance - overhang is greater in the 30Hz region than it is in the 60Hz region. This is a tight sub, but in comparison to the Rythmik, it is not as precise. You can read the review Steve posted to get Jim Wilson's subjective opinions of the differences.
Here is the PSA XS15se. You can see it is a very close match to the Rythmik! I have never heard this sub, but based on this measurement, it is a very tight sub.
Here is the SVS SB1000 (which is the model below the SB2000 you are considering). You can see quite a bit of "bass bloom" in the 25Hz region:
I believe SVS deliberately designs in the "bass bloom". I feel certain they have the expertise to tame it if they thought it would make their product better. For HT, it is a lot of fun, and if you are a typical buyer, hearing the extra power in the lowest frequencies can be very gratifying with a great degree of pride of ownership. Many people are looking for that in a compact sub (WAF) and SVS gives it to them. However, if you are looking for the ability to articulate details in the lower frequencies, the extra energy down low gets in the way.
From what I have seen, the Rythmik (or PSA) are the best options for "musical and tight".