In general, putting LED retrofit emitters into a reflector assembly designed for a traditional bulb is going to be a mixed blessing. The stock parabolic reflector is designed to handle light coming from a uniform pinpoint source (or nearly so), the filament of a standard or halogen bulb. The multiple diodes of an LED replacement source are all in different locations from that design point, so they won't result in the same cleanly focused output. Their increased brightness (lumens) may make up for this, but the output will still be more diffused. Some LED replacement bulbs make this a bit worse by putting two diodes on one side of their central post for low beam (neither at the focus point) and an additional diode closer to the focus point on the other side of the central post for the high beam.
Since LEDs are more efficient in terms of light output for power input, you'd think they should produce less heat, too - you'd be wrong. Commercial LED products, especially in the automotive world, produce a good deal of heat. There are a couple of brands that use lower than usual profile cooling assemblies, and if you go this route those are the ones to choose. Don't cheap out if it costs a bit more to get what does the best job.
I opted to simply replace the whole assembly with an LED based unit (replaces headlight shell, reflector and bulb). The power draw is lower, the heat issue is avoided, and focus is simply not a problem since each LED is behind its own focused lens.