The Microsoft Office factor
There's one other important factor to keep in mind when it comes to functionality between these devices — the iPhone 6 Plus may behave like it's a micro-iPad more than a larger iPhone, but it is still an iPhone. That means that, added functionality aside, you will still be loading iPhone apps onto it, and universal apps that run on both iPhones and iPads will treat it as an iPhone. This is particularly important where developers haven't updated an app to take advantage of the iPhone 6 Plus screen like Apple has.
Nowhere is this more important to consider than when it comes to Microsoft Office.
Microsoft did a bang-up job with Office for iPad, delivering three independent apps — Word, Excel, and PowerPoint — that replicated the core features of their desktop counterparts and did it very well. (PowerPoint has improved since its rocky start, though Apple's Keynote remains a far superior and Office-compatible presentation tool)..The features that the vast majority of business users need is contained in these apps and transitions seamlessly between iPad and desktop. As I indicated in my initial review, Word is the best iPad word processing app for a business user.
Office for iPhone, released nearly a year earlier, is an anemic single-app offering that offers the most basic functionality of Office and that eschews even the most commonplace features like true formatting support or track changes. It is one of the worst productivity apps out there for the iPhone and, as things stand today and unless Microsoft makes massive changes, that's what you'll get on an iPhone 6 Plus. That's extremely significant to keep in mind if you're considering an iPhone 6 Plus as a way to get the best of both worlds — iPhone and iPad — in one device.
There are, of course, other Office-compatible options for the iPhone and Apple's iWork apps do a great job of interoperating with Office documents and supporting many key business features, though the experience is rather different and there is a bit of a learning curve for longtime Office users.
Consider your needs as much as the size of the device
The biggest piece of advice I can offer at this point to anyone debating site-unseen between the iPhone 6 and 6 Plus and how they relate to an iPad for (either size) for business use is to be very aware of the tasks you need to accomplish and to try to picture how each will work on each of the three devices as best you can. That, as much as size, should drive your decision making. Pick the device among the three or a combination of two of the three that seems best suited to your real-world everyday needs.
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