In the case of dimmable LED’s the advantages of the direct 230VAC products makes this the preferred choice. Most often the MR16 LED lamp is not supplied with a transformer. This then not only brings compatibility of the LED and transformer into question, but also compatibility of the transformer and dimmer and in most cases the compatibility of the dimmer/LED/transformer combination. There are three very complex and physically different electronic technologies that must be optimally matched. If not matched, the lamps could flicker, dimming range be limited, lamps might not turn on at all, etc. etc. On the other hand, a 230VAC dimmable LED lamp is a complete unit which does not require additional and very much unknown electronic modules to operate. This not only makes it much easier to ensure dimmer compatibility (avoid possible MR16 flashing when turning on or off), but remove a possible weak link from the lighting system.
A good example of a maintenance issue is if the client has low voltage LED’s installed and a failure occurs. The maintenance crew must have not only spare LED lamps, but also spare electronic transformers, since they do not know which failed, LED or transformer. If the transformer failed, they should ideally ensure that the same brand and model of transformer is replaced, else the LED lamp might not react the same as the others.