Oh I know they're not "meant" to be modded, but they're also not meant to be used as Mobility drivers. Until very recently ATI's stance has been that they do not make new drivers for Mobility Radeon cards, and in order to use them a manual workaround was needed (i.e. modding, manual update, etc.).
My machine is an Acer 8104. It runs perfectly in almost every way except for the fact that it has a great inability to run new Catalyst drivers. Sometimes the releases work for me, sometimes they don't. I tried Omegas and DNA drivers as well, but I got less performance out of the Omegas (and buggy PowerPlay usage) than the modded ones and the DNA drivers completely crapped out my system. As far as modded drivers go, Half-Life 2 is always my test. If I load the game a few times and change some settings, if the drivers work I won't have any trouble. But with the new 5.5 drivers (and 5.3 and one other, for that matter) it quits in the middle of loading, shows a striped purple and black background, and refuses to let me continue with any kind of menu at all in the game. The 5.4 drivers work fine for me, so I guess I'll be sticking with those until 5.6 or the Mobility drivers are released, whichever comes first.