You can argue that it really depends on what the collected data is used for, if its just for fun or you actually have to use the data for serious purposes.
I have been working with Multibeam echosounders for a couple of years, here the latency of all instruments is of high importance, but here you also have gyro and motion sensor, so if one sensor is off by a second the result bad.
What rate does the transducer send data with compared to the GPS?
It might be worth to think about the accuracy of your GPS, compared to your speed, and the transducer "latency" during logging.
If the GPS has an accuracy of a few meters or more, how much do you gain in data quality from a correct logging time?
I must note, i dont know what systems you are using, so you might have far better accuracy if you are using an argumentation system.
see GPS.gov: GPS Accuracy