Nice looking system.
From your description, I get the feeling we have similar tastes. You can see my systems. I would keep your cartridge as you said.
I have a Linn LP12 which I bought a couple years ago at the Akurate, mid-level with a Koetsu Rosewood Signature cartridge. I have since upgraded the sub chassis and tone arm for what I consider well worth upgrades, significant sonic improvements. The Linn is small, beautiful and sounds outstanding.
One class of upgrades I consider the most significant over the last 40 years has been phonostages. They have always produced what I consider outsized sonic improvements. I found until my last upgrade my phono stage was always holding back my TT. I started with a Class A $200 Phonostage in about 1980… which I can’t even begin to tell you how terrible it sounded. I quickly upgraded a couple times until at last bought a new Audio Research PH2. From then on I never left Audio Research. PH2SE, PH3, PH3SE, PH8, and now REF3. I recommend PH8 or better for your system. ARC preamps and Phonostages… really sets them apart.
My combination is wonderfully musical with good midrange bloom, great sound staging and highly detailed. But the key words are natural and musical… the tone arm upgrade to the Ekos-se brought up the detail significantly with loosing any of the musicality.