I have had a BM 690 for three or so months, and it is now my standard "dress knife". Before I got it I did not know that I would ever have need of a dress knife, but I have been surprised by how often it winds up being carried and used. Moreso than any other knife I have the 690 is a blade that I am pround to carry and own. It is especially good for office carry, because although it is quite strong and a fairly large knife even people who cringe at my 710 react very well to it. Much more classy than your average black G10 cookie cutter knife.
Its the little things on this knife that really appeal to me, things that I have never seen on a production folder. The fasteners along the back of the handle have been machined into a nice hourglass shape to provide additional clearance for the blade. The scales have been formed precisely enough that there is no gap between the wood and carbon fiber portions, and rather than just laying the CF on the liners they have thinned out the wood to get a great sandwich effect. Theres a bunch of things liket that which are not immediately noticable but are quite impressive once you get to seeing them. Benchmade really outdid themselves on the construction of the 690, it seems better put together than any similar production knife that I've seen.
Despite all this, the 690 is no slough when it comes to actually cutting things and doing work. It has a nice pointy blade shape with a very faint recurve which gives good slicing power. The Axis lock has spoiled me on liner locks, but the 690 lock is still quite good. No blade play on mine, perfect engagement, easy to use, and makes a great sound. I would not hesitate to do anything with this knife that I would do with any other quality locking folder.
At first I was afraid to use the 690 too hard because of the carbon fiber and wood, but once I got over that and started using it for everything (including slicing the occasional industrial high pressure refrigerant line) it has held up just fine. The steel on mine is 154CM and I find it to sharpen easily and hold an edge well.
I don't have any real experience with the Lum Chinese, but I would recommend you strongly consider the BM 690. Don't make up your mind until you can see one in person, as pictures of his knife really don't do it justice.
Now if only they would make one with an Axis lock, I would probably never buy another knife.