To the best of my knowledge, here in the U.S. a horse out of Roll With Joe (sire of Twin B. Fresh), set the double-gaited record of 3:45.1 by pacing in 1:50.2 (winning over 6 figures) and then trotting in 1:54.4 at Hoosier Park.
That is clearly nowhere near having a top trotter beat a good pacer, but it is fairly impressive. Sounds like there are several really promising horses down under this year. (follow mostly on HRU and watch some of the top races.)