I run M608z's, and they are quieter, smoother, and track better than nearly every LRE tire I have ran.
The 19.5's will feel certain road conditions more, but generally ride much better.
Les Schwab balanced mine with CounterAct Balance Beads, and I couldn't be happier. They are balanced much better than other 19.5's I have been around with conventional weights.
The M608z is a very aggressive tire too, probably more than I needed and I might look into the M920 next time, it's still a decent "A/T" and carries a speed rating of 87 vs 75.