wow, how dumb, firstly these have been around for ever, they aren't solid state.
Essentially SSD's are useful because they KEEP THEIR DATA WHEN TURNED OFF. DDR, does not keep its data, its an always on device. People have had Ram drives for ages, Gigabyte had an i-ram years ago.
How much was ddr2 at its cheapest, £30 for 4GB, so a proper memory drive will cost you £480 for a 64gb ddr2 ram drive, which offers very little real world performance.
doubling your hard drive speed, doesn't, in ANY way double the speed of your system, 98% of what people do on their computers aren't hard drive limited, hence a double to 10 times faster HDD offering minimal game loading performance increases.
Thats before you take into account the systems that can use them basically have to be always on systems, that HAVE to have battery backups, which won't last long and a single power outage will wipe ALL your data making it fairly useless.
Its also not instant on or instant OS desktop, your cpu still has to do things, load drivers, drivers have to process requests and to things, yes it will load fast, but it will barely increase performance for most things.
The majority of things you do that are HDD limited, like recording uber high def video or editing/manipulating high bit rate data of any kind, will run into massive size limits to any DDR based hard drive, which makes them fairly useless anyway.
Should you want you can create a ram drive, install a game on a ram drive, run it from there, and see almost no performance improvement at all. You either save your ramdrive image to a mechanical hard drive when you shut down or lose the data, meaning when you reboot and want to play the game again, you either load the image from disc, which will take a while anyway as it has to load the ENTIRE game image to ram before it can load the game, or you install from scratch.
They are impracticle, expensive, not reliable in any way and offer no performance improvement to 99.9% of users. They've also been around for, 5-10 years, before flash drives were available and no one had them, because they were pointless.
EDIT:_ You do of course realise that the box is £299, WITHOUT memory, up to a max of 64gb of ddr2, which would set you back a further £500. Infact they sell dimms for £20 for 2gb sticks, so thats £160 + £299 for a 16gb ddr drive thats
3x faster than a $2000 desktop at booting and clicking around the desktop and opening applications and all other IO intensive operation
Then who doesn't want to be 3x faster at booting, and clicking around the desktop and opening firefox in 1 instead of 3 seconds, woo hoo. For a 64gb drive, considering it only has 8 memory slots, you'd need 8GB sticks, considering 8GB sticks are like, I dunno closer to £200 than £20, you're looking at probably almost £2k to make it a full 64gb drive, to make your desktop faster at clicking around.
EDIT:- the cheapest 8gb stick I've found so far, is £370, so thats only £3259 to make a 64gb ddr2 drive, wow, you almost sold me on that.
those were the days. These young uns don't know there born