There has been on ongoing argument, or should I say war, amongst people about which is an overall better diver. The Rolex sub vs. the Seiko MM. Do a google search and ye shall find. Personally, I like the MM and Sub for their own characteristics. I also think that the Seiko is rather cheap for what it is capable of. The hardlex xtal get's on my nerves too as the MM600 Spring Drive uses a saphire, negating Seiko's own reasoning for using it in the MM300, but I guess I could overlook it. The MM300 SD has been on my "to get" short list for some time now.
On a side note, have any of you seen that custom Seiko for the space mission? Simply awsome!