Is a separate phono pre really necessary?

I have an upgraded Rega P3 that is now essentially a P6 (groove tracer subplatter and counter weight, Rega Neo ps) that has a Soundsmith Zephyr MIMC star mounted on it. It is then connected to a Park Audio Budgie Ten SUT and then to a Rogue Audio RP-5 preamp.

This question is about the phono stage in the RP-5. Would upgrading to a separate phone preamp of around $1,000 to $2,000 be a worthwhile upgrade from the internal phone preamp in the RP-5? And if so which phone pre do you guys recommend (notwithstanding all the caveats about subjectivity). I'm thinking of the soundsmith mcp-2, PS audio stellar phono, parasound jc3 jr., maybe a Manley Chinook if I can find a good deal.

The wrinkle is the loading requirements for the zephyr mimic star: >= 470 ohms. This makes a lot of phone preamps really not suitable for this cartridge (hence premaps with adjustable loading via a pot) because of the static loading options are mostly well below 470 ohms on most phono preamps