I'm not much on the whole digital thing. I got along fine without cell phones or a PDA, GPS or digital cameras for decades. I contend most of the jobs done by these devices is better handled by more primitive means. Most of what my friends have on their PDAs could be stored on a 3by5 card written on with a stubby pencil. Most cell phone calls area waste of time and money. A GPS has advantages in speed and accuracy, at least most of the time, but I get along fine with a map and compass. In some ways I'm more a 20th century guy. More than one has said it's more like 19th century.

I only recently got a cell phone. I still keep forgetting to carry it. Then again I have has a PC since the late 70s. I'm not adverse to technology, when and where it makes sense.

As for combined devices, assuming you really need all those functions, I would lean toward combining them to save weight and bulk. But it isn't as simple as that. The size of the devices has gone down. (Remember when cellphones were the size of a brick and had a hand-set on a coiled cord?) Now you could fit a dedicated GPS unit, a digital camera, a cell phone, a PDA and toss in a MP3 player in a moderately sized pocket. So combining them doesn't save as much bulk or weigh as it used to.

Separate you might be able to share batteries. And if you drop or lose one your still up for other functions. With a combined device your screwed. The other part of this is replacement cost. Combined devices tend to go for a premium price. The exception seems to be the cell phone camera. Which is cheaper than the camera alone.

On the other hand I'm not big maintaining redundancy on my person. One Leatherman and one tiny flashlight and ... well you get the idea. I keep replacements in my truck so they are pretty much always within a couple of minutes walk. I tried carrying multiple copies on me but it got to be I rattled when I walked. I hate the "bat belt" look and feel. Feeling like I have to go through narrow doors sideways and the slight delay on movement. I like to keep it light for every-day wear. If I was camping in the deep woods I would carry more. But I'm not and don't.

It has been decades since I needed more than one knife.