Twenty-one percent of US buyers of Apple's iPhone 4S opt for the highest capacity 64GB model, according to new research.

A report from Consumer Intelligence Research Partners (CIRP) also found that 36 percent of iPhone buyers in the US were migrating from another platform such as Android, BlackBerry or Palm.

This compares to just 18 percent of iPhone 4S buyers when the device launched in October 2011 who were switching from another platform when CIRP carried out similar research. 

The 64GB iPhone 4S is the largest capacity iPhone that the company has offered to date and the survey was conducted among customers that purchased an iPhone in October, November and December in 2011. However, the sample size was fairly small - from an initial response of 6,316 people, only 365 were questioned.

CIRP also found that 43 percent of iPhone 4S sales around the time of the device's launch were made online, though this figure had dropped to 33 percent by the end of 2011.

Last week, CIRP released a separate study that showed that 49 percent of new iPhone buyers sold an older iPhone model on to the secondary market.

via Apple Insider