I owned the Quilter at one point when they first came out and I would say that it's absolutely fantastic as long as you don't find yourself needing to adjust the mids AND treble at the same time. I suppose if you play active basses with onboard EQ, it's probably not an issue, or if you're using pedals with EQ. I like a little scoop in my mids and a little cut in the treble with most rigs and I found that once I scooped a little mids with the Quilter, I was left without a treble control and it was just too bright for me. Rolling off the tone knob on my passive J was the only way to cut a little treble but I really don't like what it does to the overall tone. To my ears, rolling off the tone knob just eats all of your tone up and makes it muddy - much different from a treble control on an amp. Honestly, if the Quilter had just one more knob for treble, it might have been perfect for me.
I've never had an issue rolling my tone knob off. I used run the pick ups on my Hwy One Jazz rolled back about 25% and the tone rolled damn near off, with flatwounds, when I was playing alt-country. This was through an Ashdown ABM-500 Evo II 2x10 combo. Believe it or not, it was never muddy, but it was just deep and delicious. That's what I want to get back to, only without the weight (I had back surgery in 2002 and my back still doesn't like awkward heavy things).