Hi Adam, Your discs don't look too bad, vent holes aren't full of brake dust.
Be interested how anyone gets on with changing GTS brakes as their rubbish and outrageously expensive. MD told me front discs are £1K each!! and pads nearly £800. Disc/pad set up apparently unique to GTS and QP GTS and therefore no aftermarket pattern available as still licensed to Maserati. Only option to change discs and fit adaptor as per Noors site.
Of note is MC Set up cars have slightly different front discs with grooves and vent holes but not sure if this is why I was quoted £1K each.
I think they would benefit from stainless hoses as certainly with mine the feel is dreadful with a very soft pedal. Changing the fluid made little or no difference. I'll be chatting to MD when mine goes in for service soon but can't make any unofficial mods as still under warranty.
Let us know how you get on Adam.