Is the Porsche 911 a good investment?

The thesis

The 997 GT3 RS 4.0 is the last naturally aspirated, manual GT3 ever built and widely regarded as the finest road-going 911. With only 30 UK RHD examples from a global 600-unit production, it combines extreme rarity with the largest engine (4.0L) ever fitted to a naturally aspirated 911 at the time. Market values have appreciated strongly from the £128k launch price, reflecting its status as the swansong of an era, but have stabilised in the £240k–£450k range as the market digests earlier gains.