i think mike , the word experience is the key here .
 flintlocks , powder for powder will shoot at a lower velocity then a cap lock , do to the flash hole .. percussion caps fail  and they fail from moisture . i also again believe this boils down to a gimmick and convenience . imagine the marketing  back tin the 1820's .  basically the same as today  for the latest greatest thing .  it doesn't mean its better . doest mean it more reliable . 
 I mean really , cant we all hear it now ?
Tired of losing your flint ? how about the constant battle of keeping it sharp and in alignment .
Are you worried for the little woman  being able to  understand the complexities of the flintlock rifle , when it comes to home protection . Are you tired of that cloud of smoke  coming from the pan  .
 with our new patent percussion cap , you can simply forget about all these issues . no more messing will dull rocks  or alignments . the cap fits correctly every time. juts place the cap on the  percussion nipple , cock and fire . even the little lady can do it . also with this system you get the added benefit  that less smoke clouds your view , with no pesky flash  to blind or throw sparks at your face .
 i think we could go on and on with that . but i submit that their is a reason that the flintlock  is the longest lasting  firearms ignition system.
also for the record here . i learned on a cap lock . basically because i fell for all the sales pitches and more . but then i found one day that  they for the most part were false or just something to get me to buy one product over another .
 my wife  still shoots a capper . she doenst like the flash of a flinlock . But i chose a flintock because  through the years  of not only using both systems for hunting and target shooting. here in the west as well as the South    , in all types of weather . I find the flintlock , once learned , to be much more reliable .. but here is the key , ONCE LEARNED. its not a set it and forget it system .
To answer your question mike , yes i have had clatches . and i do have clatches now and then 

 maybe 1 in 50-75 shots . flash in the pan 

 maybe one in a great while . most times it happens when i forget to load LOL .
 had this happen while hunting ? yep i have . BUT when i set down and ask why , the finger always ends up pointing at me . IE the flint needed change and i knew it . 
 one time i had a pan foul .  i knew if i wasn't more careful it would foul .  i simply got lazy . when the time came  and the rifle didn't work , i was mad, but guess what . the only person i could blame was me . see i failed to do my part .  in failing to do so , the team lost  because i didn't  uphold my end .
so  as time goes on  more and more gimmicks come out . all designed so folks have to worry and do less and less . while  it can be said that they reduce the possibility of human error . i submit that they also reduce the possibility of human  intervention proper to a mechanical error .
 i would hope that  in today's world  the  quality of these caps are better the 150 years ago . but if so  why the % of cap failure in  just 1 tin ?. why do folks prefer one brand over another ?? surly they all are better then those made 150 years ago ?.
 but for me LMAO , when my wife's rifle goes pop , pop, or she throws away an empty tin. i just smile , Knapp alittle off my rock and keep on shooting , because she forgot and left the tin of caps open on the tail gate  all morning