You may think that one portable hard drive is very like another; and that is a problem for manufacturers like Seagate which want to differentiate their range and build customer loyalty.

The trouble is, one portable hard drive really is very like another; so what can it do? The FreeAgent GoFlex range is its answer, and Seagate has sent me the 320GB model for review.

It is billed as the “world’s most upgradeable hard drive,” though you can’t upgrade the thing you might most want to, its capacity.

What you can upgrade is the interface. The GoFlex drive has a detachable interface which in the model supplied to me has a mini USB port on one end, and what looks like a SATA (Serial ATA) connector on the other.

You can replace the interface with FireWire 800, USB 3.0, or eSATA. To give you an idea of the performance implications, this is what each of these interconnects is capable of in theory, though I have not measured the performance of this implementation:

• USB 2.0: 480 Mbps
• USB 3.0: 4.8 Gbps
• FireWire 800 786 Mbps
• eSATA 3Gbps

You can see from this that USB 3.0 is theoretically the fastest, though if I am right in thinking that the drive itself has a SATA interface, it will not be any faster than eSATA and will likely be a little slower. However, USB 3.0 is the future and will be more commonly found on PCs and laptops – except for Apple fans who now have Thunderbolt at 10Gbps – so that is the pragmatic choice. Currently though, most computers only have USB 2.0, in which case you will need to get a USB 3.0 card for your computer as well as for the hard drive.

I question whether many users will bother to upgrade the interface on a portable hard drive. They are more likely simply to buy another one, especially as capacities steadily increase, making new drives better value in terms of the amount of storage you get. The downside of the GoFlex removable interface is that it makes the drive slightly bigger than it would otherwise be.

That said, it does have an additional benefits. You can plug the drive directly into a GoFlex media dock, which will be the subject of my next review, or into a variety of other docks which Seagate offers.

There are a few other things to mention. I use both Mac and PC, and while the GoFlex drive works fine with a Mac, it comes formatted as NTFS which on most Macs is read-only. However, the drive comes with a Mac installer that offers to install the Paragon NTFS driver, which enables read-write, or to reformat for OS X.

I’d suggest reformatting for the Mac, unless you are likely to use the drive for exchanging files between Mac and PC.

I should also mention that the GoFlex drive comes with some bundled software. Seagate has done a deal with Memeo and offers to install various pieces of free and trial software.

Since you can get all this software easily enough from the Memeo website, I am not greatly impressed, though there is a free copy of Instant Backup which would otherwise cost $29.95. Personally I use Windows 7 and I am happy to use Microsoft’s built-in backup software, though Memeo has a continuous backup system that looks interesting.

Online backup, which is a feature of Memeo’s paid-for Premium Backup, is definitely a step up from what is built in, but in this case you have to buy online storage space as well as the backup software so it is not going to be cheap – especially if, like me, you have ripped a large CD collection to a hard drive.

The big question: do the extra features in GoFlex amount to enough to meet Seagate’s goal of differentiating its range? The ability to dock the drive is handy, and if you plan on using the media dock then yes, but otherwise you may not really notice any benefit, though it is worth getting a USB 3.0 drive if you can use it or expect to be able to soon.

That said, from what I can tell there is little if any price premium for the GoFlex drives and my 320GB sample worked well, though 320GB is rather small these days, and I’d suggest that at least a 500GB model makes more sense if you plan on storing multimedia files or keeping backups.

GoFlex portable drives are also available in 500GB, 750GB, 1TB and 1.5TB capacity. The sizes of 750GB and above have a fatter case: 22mm instead of 14.5mm. The 1.5TB drive is USB 3.0 only.

Disclosure: Kudos to Seagate for asking me to mention in my review that that the review sample does not have to be returned.

Buy from Amazon.co.uk: SEAGATE GoFlex USB 2.0 – 500 GB – black

Buy from Amazon.co.uk: SEAGATE GoFlex STAE104 cable – USB 3.0