Camera Labs

I decided to buy a CPL and would appreciate your assistance here.

1. Hoya's HMC is the same as B+W's MRC, right?

2. Are there any differences between the Hoya 67mm Circular Polarizer (HMC) Multi-Coated Glass Filter (http://www.bhphotovideo.com/bnh/controller/home?O=cart_accessories&A=details&Q=&sku=116781&is=REG) which sells for $92 and the B+W 67mm Circular Polarizer Multi-Resistant Coated (MRC) Glass Filter (http://www.bhphotovideo.com/bnh/controller/home?O=cart_accessories&A=details&Q=&sku=9776&is=REG) which sells for $113? Is the price difference due to branding etc, or can I expect to see a difference in quality between the two filters?

3. Are there any differences between the B+W 67mm Kaeseman Circular Polarizing Multi-Resistant Coating (MRC) Glass Filter (http://www.bhphotovideo.com/bnh/controller/home?O=cart_accessories&A=details&Q=&sku=10885&is=REG) which sells for $128 and the B+W filter mentioned above, other than the Kaeseman filter being sealed?

4. Are there any disadvantages to the sealed filter (other than price)? I think this might be a nice feature for the African dust.

As always, thanks for your help!

Anybody?

(I'd like to place my order asap)