I have the mazdaspeed coilovers, and I love them. I have tracked them a couple of times, and they are absolutely worth it. Independant compression and rebound adjustment (16 ways +/- for both.) It does lower the car, but not as much as the BCs, that is too low. The mazdaspeed coilovers are the KW varant 2s, they are just rebadged as mazdaspeeds.
Basically for anyone doing research:
If you are into performance/racing, and auto-x, GET the mazdaspeeds!! There is a reason that club mazda uses them!
If you just want something to really lower your car, get the BC.
P.s. - If you call a vendor looking for advice on which set-up to go with, just keep in mind that their goal is to get you to buy something. Talk to someone that actually knows something about suspension for advice. = )