Upgrade my tone arm?

You should consider a conversation with Tri at Triplaner- it’s a tight community and while I have not heard of your cart on that arm ( I am assuming you are looking at the new 12” carbon fiber ? ) , if somebody is running it Tri will most likely know.
and audio is a system especially transducers and dynamic components- so “ better “ is a myopic simple viewpoint. And yes, I own a Triplaner and a Lyra a known combination that yields excellent results.

enjoy your search @mulveling  gave you excellent advice

The Ortofon RS-309D is a very good tonearm. That being said I just upgraded to an Ikeda IT 407 CR1. It was a distinct upgrade from the Ortofon. Currently using it on my Garrard 301 in a Woodsong plinth with an Ikeda cartridge.

I have not owned a Triplaner tonearm so I can't help with any thoughts on that.

I would look into the Origin selection of tonearms. Whatever price range you can afford.

https://www.originlive.com/hi-fi/tonearm/

Dear @mglik : @mulveling  is rigth. Now, what do you not like abot the quality performance of your cartridge paIRED WITH THAT VERY GOOD TONEARM?

Been a removable headshell design you can change the tonearm/cartridge  " signature " changing and testing different headshells of different headshell build materials and weigth even its shape and you can upgrade too the headshell wires for a better ones and this makes a difference for the better always.

Other up-grade you can do is to rewire the ortofon internal wiring for this one:

     https://www.zavfino1877.com/4litz3ag-pure-silver-tonearm-re-wire-kit

and you know wnever hat: TriplaNAR CAN'T TOUCH THAT UP-GRADED oRTOFON, YOU WILL HAVE A 10k TONEARM.

Regards and enjoy the MUSIC NOT DISTORTIONS,
R.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     

I've been using a Tri-Planar with Lyra Kleos for a couple of years now and could not be happier.  You might find that upgrading both the tonearm and cartridge to be well suited to each other is a better way to go, but you'll never know until you've heard these combos for yourself.