As far as I know that last part is not true. iOS5 is still the same OS at its core on the 3GS. That is not the case with WP7.8 and WP8. The comparison of iOS on the 3GS and the 4S is more like a comparison of WP7 tango on a 256MB ram WP and a 512MB ram WP. The 256 MB ram phone is missing some of the OS features (like fast application switching) but it is still the same OS. WP8 is not. Older phones could have been made compatible with WP8 but MS did not go back and provide that because they did not consider it worth their time, to offer that kind of older device support would be harder for them, in some ways I don't blame them but at the same time I can see why those who bought a Lumia 900 recently are understandably upset.