Should I upgrade to a Manley Chinook phono pre-amp

Buy the Chinook. The first quality tube phono stage I had changed my vinyl life. You get what you pay for in this regard.... and the Chinook is definitely worth the price. They are holding value really well too, so very little risk for you.

I demoed a Chinook and end up purchasing it as well. I replaced a Ray Samuels Nighthawk with the Chinook. It's hard to imagine, but the Chinook is actually quieter than the Nighthawk. The Nighthawk picked up some hum due to it's location and there wasn't really any place that I could move it to alleviate the hum. The Chinook is on the same rack, but does not suffer at all from whatever caused the Nighthawk's hum. The loading and capacitance options are fantastic and really help fine tune your cart. I would, at the very least, suggest you try to demo the Chinook if at all possible.

Can anyone comment on the Chinook compared to a maxxed-out K&K phono pre?

I looked at the Chinook, K&K & Liberty. In the end I purchased a Zesto Andros for my VPI Classic 1 and Zu Denon 103.