All I can tell you is that I have two friends that have 5ers and they are very happy with their exhaust venting setups (same one you are looking at). Based on where the exhaust is on my ME, I haven't felt any need to add one, at least at this point.
2016 Jayco Greyhawk 29ME
2014 Jeep Wrangler Rubicon
Ready Brute Elite Tow Bar/Blue Ox Base Plate
Colorado Springs, CO