We regularly got 4400nm air miles out of the 900LX. Longest flight I recall was 10:50 (FSIA to LSZH) landing with circa 1250lbs and airmiles of 4650nm. Got a number of pics of the fuel page after landing to confirm air miles, times and fuel remaining. Achieved same out of 900EX by flying exactly according to book, but climbing (albeit a bit slowly) a little sooner than the book.
Kept a strict log of perf data and can confirm that the aircraft (ours) did exactly what it said on the tin, but to be honest I wanted the alternate to be pretty damn close.