Panasonic's LF-D521U has a lot in common with the LG drive in this issue – in fact, with the exception of two reading speeds, both drives have identical specifications.

Specifications don't always give a good picture of what a drive is actually capable of however – the D521 is theoretically able to read DVDs at a slightly higher rate of 12x, but this is only its maximum read speed. The D521 in practise averaged out to be the slowest reader of all three drives on this page. It had a mean read speed of 4.4x in both our data and video copying tests, which also means it's not that great for ripping movies or data. On the other hand it burns at a fractionally higher DVD-R speed than the equally rated 2x LG – it took 27 minutes 51 seconds to burn 4.32GB, compared to 29 minutes 42 seconds on the LG.

The other major difference between these two units is the type of DVD-RAM discs they come with. The D521's tray is designed to accommodate encased DVD-RAM discs, which are significantly larger but better protected than their caseless counterparts. They're also the type of disc found in older DVD cams.

Unless you're hell-bent on carrying a truckload of DVD-RAM discs around with you, having encased discs is the better option. With an average life expectancy of 100,000 burns, it's a good idea to keep them as well protected as you possibly can.

As with the LG, Panasonic's D521U is a reasonable DVD writer, and there's not a huge amount of difference between the two. With the bevy of new multi-format DVD burners (that support both plus and minus standards) now coming to market, their capabilities simply come off as average in comparison.