LED dimming isn't very straight forward. That being said I believe the URC dimmers are a typical forward phase dimmer?
This link will help with understanding the different types of LED products and dimming technologies.
The MRFA-600M is a incandescent dimmer and will have poor results with most LED products.
However, if you choose the right MLV driver with the URC MLV dimmer you probable will get good results. For example; a 12V MLV driver with LED strip lighting can be dimmed with a standard MLV dimmer.