I have had my BX-2680 for over two years.  Bought it brand new.  Have about 60 hours now.
I wish I would have read this years ago.  I have been running mine at minimum RPM, just enough to get the job done.  By nature, I am a gentle person.
My hydraulics was becoming weaker and weaker. 
I had my tractor serviced early this summer and the tech said the hydraulic fluid was very foamy.  He completely drained and replaced it.
I used to mow my entire lawn at idle or slightly above idle.  Was I ever wrong!!!
I think what steered me the wrong way was the warning to operate the tractor at low loads for the first 50 hours.  I do hope the break in was okay.  Now I know.