I think you meant the other way around? Thx being the oem and monoprice is just another dealer and branding.I guess that monoprice is just an OEM for these (and many other of their products), the 887 seems to be mostly the same as the 789, but with lower height case, different knobs, no vent holes?, and when internal pictures appear we'll see the rest.
Anyway almost every brand screw things up sometimes, I understand what you say, but you'll eventually get burned at some point even with big names, the important thing is how they react when these things happen.