Been toying with the idea of purchasing a Yamaha APX500. Come to the realisation that all the guitars I test that I like are of the 'thin' variety. THis seems a major selling point for the APX series.

Any other good recommendations I should consider with the thickness of the body being key here?
I had an APX 500 and rather liked it. Mind, my main concern was the small size and thin body as I have old and rather wonky shoulders. Worked fine for that, I could play it comfortably.

Acoustic sound was....OK. Some have described it as "cardboardy". I played in jams with other guitarists at acoustic jams and the instrument sounded pretty decent. Cut through quite well and I didn't have any problems being heard when I took a break.
The plugged-in sound is pretty good as the Yamaha electrics are better than average.

I would say.... If you want the guitar primarily to play acoustically, you'd likely do better to buy a slightly better non-electrified model and then worry about adding a pickup later.
You'll get more guitar for your money.
But if you want to play the thing onstage through a system, it should work well. It's also a "slick" little axe that plays a lot like an electric.