because if you control the shade from something other than your Crestron system, that won't work the way you intended; if you read the help doc for the module, the up_down_travel_time value only comes into play when the up or down digital inputs to the module are active. Many of my clients not only have a Crestron interface, but also have a seeTouch/pico/table top to control their shades. If you happen to have a touch panel display active "showing" the shade and someone decides to change the lift of a shade from a Lutron i/f, using only what you described won't work (in this case); the graphic/value will "jump" to it's final value.
using the analog rate limiter and setting the time value on it (same as what you would set in the module) gives you the feedback you are looking for regardless of controlling the shade from the Crestron system or the Lutron system...i.e., it's consistent.