I would say everyone's experience is different. The difference I got with the pre-trimpot tone pump and US9V in my EuroLX was amazing.
But the US9V, as great as it is, is not going to be worth the extra money for some people. limaguy put up a comparison of an 18V tonepump, a US9V in a forte, and a US9V in a Kramer NS2. the 18V tonepump and the US9V forte sounded a lot closer to each other than the two 9V basses in my opinion.
Its a great preamp, whether it gets you what you want depends a lot on the bass. heck, I think the difference between old EMG's and modern EMG's may even make a bigger difference.
Sams recording are about 50% of the equation....the other test is in a Live setting cutting through the mix (or getting lost) of drums/guitars. That will be my other test come monday and the switching of basses between settings. Then I will know how it compares better. My guitarist has an ear like no one I know. He will give me his opinion....
