I will never need another high-end dive watch!!!
I used to own the highly regarded JDM Marinemaster 300. It is a very nice watch - but this MM600 has many upgrades and is a step above the venerable MM300. The upgrades include all-titanium construction, sapphire crystal, increased water resistance, the GMT function, and the Spring Drive movement. All of these upgrades combined make the MM600 my ultimate dive watch.
First, I love the size. It is large and in-charge! Yet, the titanium gives this large watch a very reasonable weight, around 165 grams or so. It is beautifully crafted, the bracelet is a work of art. The "sawtooth" bezel looks very very cool, and is very smooth turning. The dial is beautiful, and the lume is unbeatable. The Spring Drive movement is a thing of beauty, and results in an absolutely smooth-sweeping second hand. The 72-hour power reserve is very nice, and the accuracy is impeccable. Mine is running at about +8 seconds per month.
One other thing I like... Since this MM600 is sold in the U.S., it can be serviced in the U.S. by Seiko -- unlike the MM300, which must be sent to Japan.
All in all, I am extremely happy with this watch!! AZ Fine Time offers it at a great price!! I'm so very glad it is part of my collection.