[citation][nom]fancarolina[/nom]Simply Western Digitals copy of the Seagate Momentus XT.[/citation]
No. They're actually quite different. Seagate's Momentus XT (I've got one) is not bad by any means (especially the newest models!), but it uses a much simpler caching method. The advantage of Seagate's approach is that it is done entirely on-drive and it is software-agnostic - meaning it works on any OS, and requires no drivers. In fact the OS will just think it is a regular mechanical HDD and treat it as such.
The disadvantage is that the Momentus XT is not as good at knowing WHAT to cache. A driver-based solution will be similar to Intel's SRT caching system. It will be smarter, faster, and has a lot more cache to play with. In fact, given how good some of the caching systems are, I must disagree with the author's assertion that you'd get better performance by having complete manual control over the drive.
Think about it. If you install Windows on the tiny SSD, you've got a lot of files in that installation that aren't accessed regularly. That's a waste of precious cache, and leaves less room to cache installed programs! So instead of automatically caching most of your software's commonly accessed files, you're suggesting that we manually cache ALL of the files of a more limited number of programs? That leaves the rest to run ENTIRELY on the mechanical side.
Just let the caching system learn what it needs to keep in NAND and what to keep on the mechanical bit, and in regular daily use the system will have better overall performance. It might not be as fast at a particular task, but it will be better across the board. It also greatly simplifies space management. You could shove this drive in your parent's laptop, install the drivers, and they would be able to enjoy the speed boost without worrying about capacity.
If you really want no compromise, you either have to get a very large and expensive SSD, or get a larger laptop with dual bays. I actually lean towards the latter, myself, but most people don't have two bays, don't have tons of cash to burn, and have at least some space concerns.