if you want to buy a watch for investment potential, according to some of UK's top auctioneers, you should be buying pre owned and then keeping it for several years. after that you may find a profit, but if you want a watch for its looks and soul then you need to forget about investment.
personally i am very cynical about ltd editions if over-used or if they are 'personality' editions. buying an AP ROO Rubens Barichello is IMHO a way to lose a lot of money, unless he becomes a world legend like Ayrton Senna. you need to buy it for how it makes you feel and not because it is limited in number as in later years you might find that people would rather buy the standard model than the ltd ed.
i've never heard of 'Savarona steel' so i cant comment on its relevance. i do have some ltd editions myself, the UN Ludwig perp which is a valid edition as it is an anniversary model AND it is also the first of Dr Oeshlins fully crown operated perps, the B & R phantom chrono, which is already selling over retail just for its looks although i didnt buy it for its ltd ed status.
i hope that helps put things in perspective
Graham