It's a terrible idea to mix and match drive models, because they'll have drastically different performance characteristics, and if you're lucky you'll only get

It's a terrible idea to mix and match drive models, because they'll have drastically different performance characteristics, and if you're lucky you'll only get a little worse than the lowest common denominator on all axes. What quality OEMs do is make sure they never ship you drives from the same manufacturing batch in one enclosure.