22 years on SPDs here with never a worry. Just as long on look/spd sl on the road bike, never a worry.
I had a dabble with flats on my fs a year or so ago and it all felt a bit 'meh'. Then switched to Mallets and thought I had the holy grail.
For other reasons I thought I would try out my flats again the other day (fat spanner ones, just like CNC nano techs from superstar with five ten impact 2 lows). I remembered that I had a bag is DMR Terror Pins (long ones) so I thought I would switch out some of the short stock pins for them to see what happened.
Bloody marvellous is what happened! I can't say I will never go back to clipped in on the fs but words like "stuck like glue" and "planted" come to mind with the flats. Plus the knowledge of being able to dab easily.
Long term I will worry about float, because long pins and five ten rubber don't. Short term, loving it.