A few words about the science of lighting and vision. All other things being equal, like pattern, focus, etc. the output of a lamp has to DOUBLE for it to be a practical increase for humans with normal vision. So, any swap of bulbs means you should think in terms of doubling the power, from say 50W to 100W.
That said, the usual warnings about putting double the heat into a headlamp system not designed for it apply.
Personal note: I don't like Xenons because their color looks different. I'm sure they work great, or the fine MB engineers wouldn't bother to develop them and offer them.