We've felt that many times, and expressed it to TomTom almost as many times.
So for the moment, to reiterate, and in much more detail ...
If you wish to save your old info for your GO930, FIRST back up the mapsettings.cfg file inside the map folder of your GO930 to your PC somewhere.
Delete the mapsettings.cfg file from your GO930.
Create all of your trip waypoints as Favorites on your GO930.
If you don't already have it, download the Transfer Assistant here >>>
http://uk.support.tomtom.com/app/answers/detail/a_id/14081/~/content-transfer-assistant
There are separate versions for Mac and Windows.
Fire up the Transfer Assistant and connect your GO930 and follow the Transfer Assistant instructions.
At some point, it will ask you to disconnect the 930 and connect your 'next' device, which will be your GO500.
After finishing the instructions and disconnecting your 500, you will find all of the favorites from your 930 all appear as 'My Places' on your 500.
If you wish, you can now copy the mapsettings.cfg file back from your PC to your 930.
Since the 500 will place all of your 'My Places' entries in alpha sort order, naming them as noted above allows you to know which is which. You can get creative with this, of course: 01_Minneapolis, 02_Ames, 03_KansasCity etc. or whatever works for you. By using the numeric up front, it displays them in your desired sequence.
A few things to know about using Transfer Assistant:
1) Transfer Assistant APPENDS to what already exists (if anything) in My Places in your 500.
2) There's supposed to be an upper limit of 96 'My Places' items on the 500. I found that this isn't true... see below.
3) Never load up more than about 40 at a time or you'll get duplicates. If that means creating favorites on your 930 more than once to get a total of more than 40 entries, delete the first 40 from your 930 and a fresh load of 40 more on your 930 before moving them to your 500.
4) If you follow rule #3, keeping in mind #1, you'll discover that it will hold a lot more than 96 entries, and you can avoid duplicates.