I ran the Speed-Pro division of Federal-Mogul for 12 years. In that time I supplied rings to many of the premier teams in racing - - NHRA including Anderson (4 time champ team), Reher, Jenkins etc., NASCAR included Roush. All guys that had the finances and research budgets to run any ring that gave them any advantage.
We has the country's finest reseach lab and dyno setup for ring development - - Cray computers, many dynos, radioactive exhaust analysis for
oil consumption, etc. (O.E. money). No gapless stuff after many dollars trying it.
A 3 thou increase in gap is virtually insignificant in anything less than a Pro class application - - and a thou of wear is a pretty good number after many thousands of miles. Gapless rings will show the same leakdown numbers even when the working face of the ring is completely worn out. Dynamic seal will be shot - but that guage still looks nice....