Years ago my club ran cars with rather powerful magnets. I did not care for those because the cars were so stuck down that you could often run them flat out around the track and they were also "all or nothing" in that they would crash with no warning, often with damage to the cars. Eventually we reduced the amount of magnetic downforce and moved the magnets forward so that the cars would slide before they came out of the slot. After we switched to routed tracks magnets became useless except as weights.
If you chuck the magnets any defects that a car might have will be more apparent, in order to fix those defects you will need to do some tuning and you may have to spend some money on aftermarket parts. Even more expensive cars like Slot.its and NSRs, which come with good parts, will need to be tuned if you run them without magnets.
I am aware that there are a lot of people that just want to take a car out of the box and run it. If that is the case you would probably be better off with sticking with magnets. If you find that you don't like cars that are glued to the track you can always reduce the amount of downforce as I mentioned earlier.
Here is an article on tuning cars for non-magnet racing:
https://drive.google.com/file/d/0BzLR42 ... sp=sharing