I have only one barrel with QLA, interesting enough on one of my two Big Boar 58's. That's been handy for comparisons.
Basically the complaints about cutting at the muzzle with "standard" patch thickness are accurate. Or at least the QLA will quickly tell you the knife is starting to dull a bit. After that the complaints seem kinda funky in my direct experience. No issues, and no loss of accuracy.
In truth I do a high proportion of my shooting with a loading block, and the QLA is a non-issue. Heck, the 58 cal bore is just big enough I can use my little finger as a "short starter" and just shove the ball out of the loading block and below flush in the barrel. Actually darned handy not to be fiddling with a short starter.
This is a whole long ways from the original question about REALs in a NE 54. No sweat whatsoever. They slip right into the bore of my 54 NE and stop at the top band just like they supposed to.
WHAP with the short starter or the side of a knife handle, and they're started and easy to finish seating with the rod. I tried "thumbing" a few past the top band, and I'm just not man enough. No need for a micrometer or a molecule of worry if your NE 54 has a standard bore.