Pretty much yes. :)

ShieldTV does gaming better, has a Plex server builtin and has way better hardware for gaming (plus newer Android probably), but if your Sony does everything you want, there's no real reason to make your setup more complicated.

(I'm in the same boat, my XD93 is good enough for everything I do with it, even though it can be a bit slow.)

If all you want do do is local NAS media playback, then any of the cheaper options like Fire TV/Stick or even, probably, whatever is built in to a modern Smart TV should be fine.

The advantage with the Shield is that it's far and away the most powerful (CPU and GPU) media box. This means it can potentially do a whole lot more than streaming media ... like nVidia game streaming from your PC for example.

It's great for emulators as there's lots of Android ones that can be installed. Plus the horsepower under the hood makes for high quality emulation. Obviously, great for Android games too and there are also some very high quality games developed specifically for Shield too.

It also has support for the big three streaming services ... Netflix, Google and Amazon. Cast capability is fantastic to have, courtesy of the Android TV operating system.

Plus it can act as a Plex server , if you are into Plex.

So if you desire the extra power then it's a very good deal but it may be that a much cheaper solution is adequate for what you want to do.

TL;DR If all you want to do is play media from a local source, you don't need it. But if you want the best streaming support plus great game support plus lots of power, then it's worth the price.

Is it pointless for me to drop £180 on a Shield TV box?

For you, yes.

If you're happy with what you've currently got, then I see no reason to upgrade.

High res audio ... if you have an AVR capable of handling DTS-MA, TrueHD, and DD+ you can't get those streams through ARC or optical.

I have an old Sony 2015 810c and it's a slowwww piece of shit so I'm glad I have my Shield underneath it but the modern ones are plenty speedy

Yeah go ahead & spend £180 on a Shield TV and then realise that it outputs lousy 1080p > 2160p(4K) video upscaling picture quality compared to any smart 4K TV you care to use 1080p/4K video streaming Apps on.

Why is this the case ?

Its because Android media players do not do Auto 1080p <<-->> 4K Resolution switching that would allow you to optimise picture upscaling outputs from various Apps.

1080p video streaming Apps running on a smart TV will already have their picture outputs upscaled by a 4K TV's superior upscaling hardware.

This applies to ALL external Android media players - its a dirty little secret no one tells you about.

.

The next Gotcha is Android TV streaming Apps like Netflix and Amazon Video, running on an external media player will not output 5.1 Audio unless you are HDMI connected to a EAC3/DD+ HDMI Audio receiver. So expect 2.0 PCM Audio only if connected to a AC3/DD only TV / Soundbar.

.

One important thing external Android TV media players do well is AC3/DTS & HD Audio passthrough when using Kodi. Sony TV's have lousy, custom hacky Audio handling for use with Kodi. They cannot even do 5.1 DTS passthrough as an example.

Only advantage in your case might be the possibility to just take shield tv with you when you go to some trip.

then if you can get it to online or with say external hdd with some good movies, those moments I bet that you would be better suited with shield than your current Sony TV.

However if portability isn't your thing or you would like even more portable chromecast option, then your current setup is more than enough.

i dont know what your sony tv can do, but the nvidia shield comes with android tv, so you can basically install any android app like emulators, games, apps ..

if the only thing you wanna do, is streaming local content, you should be fine with your tv