A close study has shown that opening the doors to iPhones at large-scale business has not only made workers happier but has often saved money over competing smartphones in the process.

In a report issued last week, Ted Schadler of Forrester Research has presented an about-face for the research group’s attitude towards iPhones that recommends businesses consider the devices for their network and that many users are genuinely more interested in accessing work content on an iPhone than on corporate mainstays using Microsoft or RIM software.

Using the web is a “chore” on a BlackBerry but intuitive on an iPhone, Schadler writes, and many workers are ultimately happier when they can pick their phones instead of having that choice dictated by IT.

Where Forrester had previously warned companies to avoid iPhones when possible due to the high phone prices and lack of security, it now says that many of these legacy worries have been softened significantly in the wake of Apple’s iPhone 2.x firmware and uses Amylin Pharmaceutical, Kraft Foods, and Oracle as examples of how permitting the phones ultimately helped their respective bottom lines.

Amylin’s senior IT director Todd Stewart describes iPhones as being easier to support than “other mobile platforms” and that iPhone 2.0’s hooks for Exchange calendaring and e-mail meant it only took three days to ready the 3,000-person firm to support iPhones. The relative strength of mobile Safari and the e-mail client has led many to treat their systems more like netbooks than mobile devices.

On a pure cost basis, the phones themselves are less expensive to run: their combined plans save about $360 per year, per phone. Stewart adds that individual ownership of devices, instead of handing them out from a corporate pool, has also trimmed costs by persuading workers they should be more careful with their smartphones.