Tiagra 30WLSRA versus ???

I'm looking at updagrading with a new reel.

I currently have a TLD15, 25 and Tiagra 16. All spooled with Braid (10kg and 2 x 15kg).

I want to setup a decent trolling outfut and was thinking about a tiagra 30WLSRA, rigged with 24kg.

This is pretty expensive, so will probaby team it wup with 24kg backbone  t-curve (cheaper than the Shimano tiagra rod).

Plan is to use this for trolling the FADs and exmouth.

Any tips for whether to use braid, mono or braid with a mono topshot?

Is it worth spending the extra $$ on a Tiagra, or should I save a bit of coin and just go for a TLD30 or similar?