I've had mine for a month so I don't have any experience with long term issues. New orders come with the newest version of the fence. I haven't used biodegradable liners or had problems with the seal strips so can't comment on those.
The bulk charcoal filters on Amazon are identical to the ones Whisker sells. Ditto for Freshwave packs though I believe the orange scent is unique to them.
I have a long ramp intended for dogs covered in litter trap mats. You can see a picture here:
https://www.reddit.com/r/litterrobot/comments/13qmpwn/my_litter_tracking_containment_setup/