This pretty much says it all. But wait...!
Since I own both (for the moment) I thought it might be fun to compare two mid-priced Japanese automatic divers, the Seiko SBDC001 (nicknamed the Sumo by the WIS crowd) and the Orient WV0031EL (known as the M-Force, from the printing on the dial.)
The Seiko SBDC001 Sumo
The Orient WV0031EL M-Force
First, the similarities: both are Japanese automatics with manufacture movements. Both are designed for scuba diving, and meet ISO standards. Both are big, heavy, tool watches. The Sumo's street price is about $600 US, and the M-Force is around $500, so they're both in the same price ball park, although it appears a little more difficult to get the Sumo, it being a JDM product, whereas there seem to be plenty of e-tailers who sell the M-Force, which might explain the price difference.
The Sumo is a bit smaller of the two, measuring 44.35mm three-nine, 48.11mm with crown, 50mm lug to lug, and 13.9mm tall. The M-Force is 46.21mm three-nine, 51.5mm with crown, 51mm lug to lug, and 14.5mm tall. Both watches have the iconic Japanese crown at the four position. Both are rated at 200 meters, and both have the term "Air Diver" on the case. Both watches hand-wind and hack.
The biggest difference, obviously, is the Seiko's dial is black and the Orient's is orange. Other differences: the Orient has the power reserve. Some like the PR indicator, others don't. I don't really have an opinion one way or the other, but I think it's a bit more important to have this complication on a watch that doesn't handwind. The Seiko's dial is somewhat less cluttered. The Seiko also has slightly fatter hands and a larger lume pip on the seconds hand than the Orient. The hour markers are also a bit larger on the Seiko. Combined, this gives the Sumo a little better low-light legibility:
While the Orient's dial is a little cluttered, it's perfectly legible. Both watches easily pass the Conjurer-quick-glance-inside-a-dark-car test. One issue with the Orient's dial: it moves! When you unscrew the crown and pull it all the way out to set the time, you can actually see the dial move ever-so-slightly.
The Seiko's bezel is a standard aluminum insert with a divers scale. It's partially shrouded by the case sides, so it's a little difficult to turn unless you have your fingers at the twelve and six positions. It turns superbly, with almost no backtracking. It feels like a high-quality bezel should.
The Orient's bezel is what appears to be a two-piece construction, with a black IP inner insert and a stainless steel outer flange. I should note that the example I own I bought second hand, and a previous owner had the outer flange bead-blasted. Standard NIB M-Forces will have a shiny polished outer flange. The Orient's bezel feels less substantial. There is more backtracking. It is also more difficult to read at a glance.
The Sumo has one of the most beautiful cases you're likely to find at anything close to it's price. It's got a mix of high-polished and brushed surfaces; the case itself is fluted and the machining is top-notch. I've seen a very good comparo with the Sumo vs. the Omega Planet Ocean, and considering the price difference, the Sumo held it's own.
The Orient's case is well made, a little more utilitarian that the Sumo's. It's got nice architecture and it's well machined. Here's a pic of the Sumo's case, with crown, compared to the Orient's:
A bit of a draw, here. I like them both, although the Sumo's case obviously has far more hand work that went into it.
Here's where the Sumo starts jumping way ahead. It's bracelet is very good (although not as well made as the case, however.) There's a lot of angst out there concerning the Seiko's bracelet--many guys otherwise love the watch but get PO'ed about the bracelet, thinking it too narrow for the watch (it's about 20mm.) I personally don't mind it; I think it holds the case to the wrist fine, and I appreciate the fact that a slightly slimmer bracelet sheds a few grams of weight. The endlings are solid:
And it's nicely made, with a nice fluid drape:
And the clasp, which may well be the exact same one used on the famous Monster, is all right, but cheap. It does offer a westsuit extension:
The Orient's bracelet is, well, a piece of crap. There's really no other way to say it. It's cheap, it's flimsy, it's got hollow endlinks:
And worse of all, it binds:
One thing I can say for it, at least it stays together, unlike the first example I owned, which popped pins like nuts, something other M-Force owners reported as well. Both Seiko and Orient use the totally stupid pin-and-collar system, but Seiko's works, and on at least some of the M-Forces shipped, the Orient system doesn't.
Again, the Sumo wins. The quality of the Sumo is so high that it makes one wonder how Seiko was able to get it out the door at six hundred bucks retail and make any money on it. To get something of it's quality with a Swiss name on it, you'd be looking north of a couple of grand. It sits well on the wrist, it looks far more expensive than it is.
The M-Force feels like a five hundred dollar watch, or somewhat less when you focus on the bracelet. It does have a few things going for it that the Sumo doesn't, however; you get a sapphire crystal with the Orient, while the Seiko uses (I guess) Hardlex mineral. The two Orients I owned have both been extremely accurate, within a few seconds a day, while the Sumo is about +8-9 seconds a day. Also, the Orient, even with everything that's going against it, is a cool watch, and it's not a terrible one, either.
Overall, I suppose it all comes down to personal preference. If you're looking for a quality Japanese auto-diver, save up another hundred bucks and buy the Sumo. If the dinky bracelet will drive you nuts, spring for the M-Force. Buy what you like, but the Sumo pretty much mops the floor with the Orient.