[Simlasa]

I haven't used them, and never liked them... but I've heard/read of people using them in ways that were 'in story'... such as saying they represent a tremendous effort and applying them PRE-ROLL to actions the character would think were particularly important... more like 'betting' on the stuff you care about ahead of time rather then waiting till you mess up.
That always sounded kind of reasonable to me... and I've considered trying such things (but haven't yet).

I REALLY dislike the idea of re-rolling or any other sort of revisionist actions though... so even if I were to try using them I'd never use them to allow roll-overs. To me it disrupts the flow of the story...
'You swing at the goblin and miss'
'No I don't, I use a fate point'
'Ok... you hit the goblin'
etc.

Luckily none of the guys I play with seem all that keen on them either...

One of the guys, when he GMs, runs WFRP... and we have them in there but for whatever reason they don't come out much... maybe because it seems to fit the setting to fail/die in lots of horrible and ridiculous ways.

All that being said, and as we established on these forums a while back... neither I nor most anyone else seems to have a problem with them being in the BRP book... AS AN OPTION.