The iPhone 6 release date could come a little sooner, as Apple feels the mounting pressure of smartphone users turning their attention to Samsung Galaxy rivals, with large screen emerging as the top lure for gadget buyers.

According to the recent report by the American Customer Satisfaction Index (ACSI), the 2012 Samsung flagships - the Galaxy S3 and the Galaxy Note 2 - were the most popular choice among gadget buyers, garnering an identical 84 points in the study.

Apple's iPhone 5 and iPhone 4S only scored 82 points, also identical, pushing them down to second spot. The Galaxy S4 was not included, as it was launched after the ACSI study was conducted.

The GS3, in particular, was called by ACSI as a game changer, owing to its 4.7-inch screen that dwarfs over the iPhone 5's 5-inch viewer. And the same thumbs up were extended to the Note 2's 5.5-inch, hulking over the 3.5-inich panel of the 4S.

The study underscored the reality that large-screen smartphones, especially those being produced by Samsung in huge numbers at a dizzying pace, were increasingly gaining more traction against the screen standard that Apple insists is the optimal for mobile phones.

The numbers could prod Apple that the time to upgrade was here, though it is unlikely to happen via the iPhone 5S release date set for late September. Production of the handset was reputedly already underway, and implementing a major revision would only lead to serious delays.

Besides, the 5S form factor was decided long ago, and it was a near-replica of the iPhone 5, according to analysts.

The safe bet would be the iPhone 6, which, according to earlier reports, will have a screen size ranging from 4.8-inch to over 6 inches.

While Apple CEO Tim Cook was playing coy on the matter, he did not discount the possibility of the tech giant producing an iOS smartphone that stretches the screen size currently found on the iPhone 5.

Mr Cook hinted in earlier interviews that so long as technology trade-offs are addressed, bigger-sized iPhones are not totally impossible.

In any event, Apple was believed to be prepping for an iPhone 6 release date by the early part of Q1 2014, in the process delivering a new design model and iOS 7 killer features with the gadget, according to analysts.