I have a Primaluna HP Integrated and Revel F208s. I did a big evaluation of phono stages a year ago (over a period of a year), and ended up with the Chinook. I had the PhonoBox DS in the house for evaluation, and this is my first-hand experience.
I started years ago with the Jolida JD9, had it for several years, and modded several times. Then went on the upgrade path. Listened to these: Chinook, Project PhonoBox RS, Musical Fidelity Nova II battery, TubeBox DS, plus a few others. I had the MF for 6 months, and then brought back the DS, RS, and later the Chinook to compare. I really liked the DS. It had a nice balanced FR, and easy to listen to, but by comparison (especially to the RS) it was a bit noisy. Better than the Jolida, but still had tube rush in the background. The RS was far quieter, and the loading options are fantastic. Next to the MF, the RS was easier to use, much more musical and easier to listen to... but somehow it was a bit clinical and dry. So after all was said and done, we ended up with the Musical Fidelity. But 6 months in, I wasn't happy with it.
Then comes the Chinook. It was no comparison. Yes, double the cost, but wow, the improvement. Even my GF who thinks I'm crazy completely agreed. It has a more natural sound, never fatiguing, plenty of detail, fantastic separation of the instruments, great soundstage. Love it. When I put NOS tubes into it, it was just the perfect icing on top of an excellent cake. I have the NOS tubes that now come in the Upscale Audio SE version.
One day, a local guy contacted me and asked me to bring the Chinook over for a comparo. He had the Allnic, Herron, Sutherland 20/20 in house, and we listened to them compared to the Chinook on a VERY fine system... $25k TT, for example. My evaluation (blinded as best we could) I liked the Chinook most, then Herron, Allnic and Sutherland. The Herron was a bit more forward in his setup than the Chinook. All sounded excellent. But, I liked the tone and balance of the Chinook best. Of the 7 or so who voted, Chinook was the winner, but only by one vote. Herron was second.
Now, to answer your question, we could probably agree (or not) that Herron could be better in some systems, and Chinook in others. But, the Herron costs double. So, for me, moving up from $800 Jolida to $2500 (retail) Chinook, I don't see a reason to go up to almost $4k for the minimal difference in sound quality. For another $1500, I'd expect to be blown away, and I wasn't.
The difference from the $1k MF or Project RS, or even the $800 TubeBox DS... the step up in sound quality was definitely worth it. After evaluating and comparing phono stages for a year or more, we've settled on the Chinook and have had it over a year.
Long answer, but yes I did this same upgrade as you are considering, and yes, it was worth it.