Further confirmation/correction/etc:
Ignore the dealers - go by the book. Drain and refill at 150k
There is a filter in there. I know, I tore my old transmission apart. It's encased in metal and is, maybe, 5x6x1 inches. You don't replace it.
IMO, its not the bearings that fail but rather is a press-fit ring that slips, allowing the shaft to slop sideways and start rubbing/wearing the case and, in mine, shearing off gear teeth corners.
Don't use engine braking. I can't prove it but still feel my failure occurred at the end of a long run using engine braking - horrible clunk and nasty sounds.
Otherwise, drive normally and don't worry too much. Aside from the transfer shaft problem, I think the HF35 is an incredible design - no clutches, no shifting, etc.