I have been using the GW-52 8 times without problems so far, with the "Auto clear"option checked to delete the data after downloading (using VMWare on Mac OS X 10.9).

Today, the download stopped at 58%, and produced only a partial .sbp file. The good parts of the session are missing. Despite the download problem, the GW-52 Util software proceeded to clear the log data. That is darn stupid software design (and I'm not talking about the ca. 1980 user interface)!

So, unless you want to risk loosing data, don't use the "Auto clear" function in the GW-52 utility.

When the problem occurred, I switched to another program instead of waiting for the download to complete first, as I usually had done. That never has been a problem with any other software, but I'd not be surprised if the GW-52 Util program is unaware of potential delays on multi-tasking computers. The "log" area shows 4 timeouts and retries before it gave up, and went straight on to deleting the data that it has failed to download.

I was very concerned when one version of the software didn't have the log clear button, I always reverted to an earlier version that did, so I didn't have to use autoclear.
That button always worried me.

I have done the 'download and clear' 40 times so far without an issue. But, I'm using Win 10 and always wait for the 'download and clear' to complete before performing other tasks on the computer. The 'two step' approach is certainly safer.

This seems to be a Mac and VMware specific issue.

On the Mac using VMware I have had that happen as well. Now I use Utility version 1.4 which has a separate CLEAR LOG button and seems to suffer a lot less from the timeouts as well. I download first and then clear log. I have not had a problem since.

For users of Windows based machines it does not seem to be an issue at all. I have never seen the timeout on them. However, downloading first and separate clearing is probably a good procedure just for added peace of mind.

I use windows 10 and 7 I have always used auto clear and never had a problem nor did I worry about losing data until a resent visit after sailing with Daff so I think I will from now on just download the file then clear it as Daff told me to.

I've had no issues on windoze 10.
Also, I asked locosys to add a clock to the lock screen, which they did in a few days, so email them your concerns (I doubt they read seabreeze!).