I never really thought about this before until I decided to send a customer some information about HDU. For me, HDU was HDU regardless of brand - sort of like if someone asked for a kleenex they'd still get a tissue. As I"m researching, I see there are more than a couple of companies that manufacture HDU. Comparing like to like (15lb to 15lb etc) is there really much of a difference between the difference HDU's? Thanks.