I have 4 of their lights. M40a MC-e, m30a r2, m10a r5, and m20c r5. All of them are great. I use the m40a the most, medium on that light is very bright. The m20c on medium is quite a bit of light and runs for 15 hrs! There have been some that say their runtime is also over rated. I can concure from the tail cap measurements that I have made the m10a will estimate 5 hrs on medium when it is supposed to be 10 hrs, but 5 hrs is still great for a single aa.
I will say that their lumens are a bit over rated, as I doubt the m40a puts out 500 otf on high, but they don't advertise out the front. The m10a is quite a potent little light, that I carry with me when I go on walks.
I have had a slight issue with the m30a in that the head, when tightening to the body, you have to give it alot of pressure, but it looks like that is a result of the brass contact being sunk into the plastic in the head, making the contact requiring more turns then there are threads. I talked to my dealer, and will send it back to him, and he said he would get it repaired. Otherwise I like all of the Sunway lights that I have purchased. For the money, hard to beat.
I do also own Surefires, and love them too. I would look to the surefires for a light that had to work, only because the Sunway lights have not been out long enough to speak of durability. One note, I have a surefire e1l and compared to the m10a(i know they are 2 diff kinds of lights) the switch on the e1l is much more durable looking, as the spring at the base of the switch is soldered to the base of the body(as far as I can tell, please correct if I am wrong) whereas the surefire is a removable(easily) switch and is very robust. Again, for the money, you cannot go wrong, in my opinion.
My .02.
Tony