The mcculloch stuff is pretty good, its about the best of the non-oem kits out there. As far as lifespan goes, from everything i've heard a year for the bulbs should be no problem, and the balasts and other wireing should last the life of the car if they are installed right and not abbused.
The whole problem with hid conversions is the very reason you'd want to convert in the first place......they put out more light, 2-3 times as much light as a standard halogen bulb. Now, the beam pattern issue is where it gets complicated. These newer hid conversion bulbs put the light emiting part of the bulb in the same location as the halagon counterpart, so hypothetically, they should have a very close match in terms of light pattern. But nothing can change the fact that they're brighter, and halagon reflectors/projectors just wern't designed to deal with that much light so you end up getting a lot of stray light simply because of that fact.
Now, this is not to say its impossible to convert to hids. If you live in an area where there aren't that many people driving on the roads at night, then a direct swap would be alright. However, there really is no substitution for retrofiting in an actual oem hid lamp housing to give you that true cut off beam pattern.
Anyway, sorry if I started rambleing off there, and I hope this helped.