Using a proxy spoofs the SERVER into thinking you have a different firmware version than you actually do, not your ps3. There is no way to fool your ps3 into thinking it is a lower firmware, and even if that was possible, you wouldnt be able to install full games with the alternate proxy method as the system files on your ps3 would still be those of 2.10. The ONLY way you could get back to 1.60 is if you had previously dumped your ps3's firmware with the infectus mod chip.