John,
Though we have not used our Garmin with S&T I am not even sure the one we have can do the transfer - but we are talking about getting one of those 7" ones - probably the $220 one - then we might get into planning on S&T and sending it to a Garmin.
I also started using the route tracker function in S&T and then saving the actual route - name it from / to - and date it as part of the Save As. I keep folders of my routes and tracks by year and month so I can use them again or I can give them to someone who has either S&T or can USB to their Garmin. So a sort of diary of our trips right on a map of the trip. Of course we do not travel every day so the monthly folder will only have those days we travel.
I have also learned to use the Avoid Area function in S&T a year or so ago so now use that to force the route we want to take.
So many more tricks in S&T I still have not heard about.
As far as the Tom Tom question - the users would have to know what their devices are capable of. If you lead a caravan and have planned your route in S&T you can save it to a stick and put it in any other computer that has S&T installed. For $20 on Amazon anyone can download S&T to a PC - (sorry Apple users). Maybe Tom Tom has a website that explains. I am not even sure you can transfer from S&T to all Garmins - only specific Garmins - maybe someone out there has a Tom Tom and can explain.
For $20 S&T has to be one of the best buys there is - which is probably why MS has stopped issuing new ones each year with improvements and updates. They do not sell enough of them for it to be worthwhile. People are still using 2007 versions instead of getting new ones. For $20 why not upgrade each year? I have found reasons to get a new one every year so far. Last year some 180,000 miles of new roads and over a million new POIs - not to mention new functions I have not learned about yet.
This website . . . http://www.laptopgpsworld.com/ . . . has forums where many experts can help with tips and tricks.