We started off by taking photos at the camera's default 18 megapixel mode, recording our images as high quality jpgs. This resulted in files of around 5MB in size, which we quickly learned took some time to upload - 24 seconds to be exact. While an acceptable speed for more casual use, this is a bit tardy for those needing immediate results - such as when live blogging or writing quick news. As such we tested again with image quality set to a more lowly - but eminently useful - 7 megapixels and at medium jpg compression. This resulted in files of around 1.5MB in size and took a mere 12 seconds to transfer. To really test the card's mettle, though, we set it to RAW JPG (you'll also need to enable RAW transfers in the Eye-Fi software settings) whereupon it took 100 seconds to transfer. All told, there are faster wireless solutions if you're willing to buy the expensive proprietary adapters available for some DSLRs but for general use the Pro X2 impresses.
One point to note, however, is that you are of course reliant upon the quality of the wireless network to which you are connected, and in public spaces speed can be pretty ropey. Moreover, for every new network you encounter, you will have to pop the card into your computer, open the Eye-Fi software and manually add the new network. In both instances, though, you can rely on the Ad Hoc connection instead.
Ad hoc allows you to use your computer to create its own private network to connect to with the card, so you can snap away to your heart's content - even in the middle of nowhere - safe in the knowledge your shots will find their way to your computer. The downside to Ad Hoc is that you'll be disconnected from any other wireless networks while you have it enabled - obviously for our aforementioned news writing/live blogging scenario this isn't ideal. Connecting to a wired network as well will solve this.
While snapping away, you can have your photos tagged with a geo location so you can then map them onto Google Maps or such like at a later date. However, this tagging is done via the IP address assigned to your computer when connected to a network, which if you're in the back of beyond using an Ad Hoc network won't work. Nonetheless, it's a neat extra.
The final piece of the Pro puzzle is its public hotspot access. This is powered by Easy WiFi and allows you to input your login details to either Easy WiFi's own public WiFi service or it links up with thousands of other providers. It, along with a number of the steps involved in getting the Eye-Fi setup, is a bit of a faff to get going but once done so is a breeze to use. Explorer and Pro cards have 1-year's free HotSpot access or you can upgrade a lower range card for $24.99.
Universal features available to all Eye-Fi cards include the ability to upload photos to the Eye-Fi online store for safe keeping as well as share them with sites such as Facebook, Flickr, MobileMe, and Picasa. You can also have the card continually delete photos from its internal storage once they've been safely uploaded so you never need cleanout your card again.
When it comes to price, the Eye-Fi range doesn't come cheap with the entry level model costing around £45 and the Pro being around £100. This compares with about £5 and £10 for standard SD cards of the same capacity. However, for the range of features on offer - and bearing in mind you should never need buy another card - they all seem fairly priced.
There's no doubt the Eye-Fi range has a niche appeal: being able to wirelessly transfer photos from your camera to your computer is something only so many people need. Moreover, the extra features brought about by the Pro X2 version of the range are even more specialist - most amateurs won't need instant RAW transfers for instance. However, if you're an enthusiastic photographer who works a lot while out and about and needs instant access to your photos, the Eye-Fi Pro X2 is an awesome purchase. It doesn't come cheap but compared to dedicated proprietary wireless solutions, it's a bargain, and of course it will work in any camera.