RPM and Engaging Gears

[Hudson Force]

I recently replaced my shaft, carrier bearing, stuffing box & cutlass bearing leading from my year 2000 4JH3E Yanmar and Kanzakee transmission. With the smooth and quiet new carrier bearing I had noticed a ticking sound when I idled down to engage gears. A respected and knowledgeable Yanmar mechanic advised me that this was "back lash" from low idle and of no concern. He said that it's best to keep the idle at no less than 850rpm. I do normally idle between 850 and 1000 rpm and do not hear this clacking or tick, but I can't help but think that the lowest rpm is advisable when engaging or disengaging gears; however, the mechanic said keep it at 850rpm and it's best to hear the "thud" when you change gears. It seems counter-intuitive to me to have parts moving faster when slaming them together, but I've been wrong before. So what are your thoughts? Keep the rpms up to 850 while engaging gears or press it down to the rougher riding 450rpm for the engagement?

[Blue Stocking]

With Hurth HBW series, they all seem to rattle at idle. Its when you don't hear the "thud", you worry.