Ok I have tweaked it a bit:
if (s3 > s2 && s3 > 0.499 * (s2 + s1)) ans = HITT
else if (s3 > s2 && s1 > s2) ans = POLARIZED
else if (s1 > 3.99 * s2 && s1 > 3 * (s2 + s3)) ans = BASE
else if (s1 > 1.4 * s2 && s2 > 1.4 * s3 && (s3 /all) >= 0.05) ans = PYRAMIDAL
else if (s1 < 4 * s2 && s2 > 0.5 * s3) ans = THRESHOLD
else ans = UNIQUE
So for PYRAMIDAL s3 must be at least 5% of the total and each easier zone at least 1.4 x the one below it. Looking at my own data this did convert some threshold classifications into pyramidal, correctly IMO.