I live in the land of the Dudleyas (mostly California/Baja California coastal species, none extending much further north or south of that range) and they are wonderful plants. As tarev notes, they do not like cold or heat (though there are a few plants from the desert which do better under those conditions). Most Dudleyas come from moist, cool, mild coastal locations with regular fog, especially at night. While they may grow in day-long sun in habitat, most do much better with some protection where it gets toasty. All prefer excellent drainage (at least 50% rock).
You can tell Sempervivums from Dudleyas (among other ways) in that they tend to have little hairs along the fringes of the leaves, while Dudleyas do not; and they die after flowering, while Dudleyas live on. You can tell Dudleyas from Echeverias (a more closely related group) in that they do cannot be propagated from leaves, while Echeverias usually can; and while all Echeverias make tubular flowers, there are some Dudleyas which make open (flat) flowers.
In my experience Dudleyas are vulnerable to hares but relatively unpalatable to ground squirrels. They are far better than Echeverias at handling our predictable months-long drought every summer (and do quite well with no supplemental water). If you live in a place where summer heat is prohibitive, you can bring the plants indoors to give them a break during this period (which is when they normally go dormant). However you need to provide them a very bright location (hours of daily sun, the most light possible) if you overwinter them indoors. Winter is generally their season of growth and they require strong light to do well.
