Great question, Ray! I'm now wondering this, too (I do most of my work on the potable water side, but am getting involved in more storm projects).
Our firm recently performed a pilot project with one of our clients where we used Collector and high-accuracy antennas to collect storm drain assets. We may have used a mix of centimeter and sub-meter units for this. I will ask our editors and analysts if it made much difference to them when they were cleaning up the data before delivering.
My hunch is the most important part would be the difference in vertical accuracy. But I believe we used the separately measured invert distances and LiDAR data for critical elevations.
