insight technologies was on the cutting edge of small lights, in particular weapon mounted lights, about 5-7 years ago.
they are way behind on the led front, and since their early pistol lights, have more or less copied surefire designs.
feniz/nitecore are currently on the cutting edge, and clearly not resting on their successes. new more powerful lights, in small packages, and using readily available batteries, are constantly being introduced. and all this at about half the price of a comparable surefire (at least regarding brightness).
surefire's customer service and unit durability are second to none, however for the vast majority of people they will find a fenix more than suits their needs.
i recently switched to a nitecore for duty use. manily because of the size and lumen output, which is significantly brighter than my surefire u2 (which retails for nearly $300). and their new piston drive tailcaps are innovative at the least. we'll see how it holds up, surefires are workhorses, and my u2 is still going strong (though i broke the lense, which was replaced at no cost by sf, as well as a circuit board upgrade).
also, dont be sold on purely on lumen output. there is definitely a point of diminshed returns. in a standard 2 cell light, 100-150 lumens is more than sufficient, heck, even a well placed beam of 50 lumens is quite disorienting. over that you really aren't going to see a noticeable difference unless the increase is on the order of a 50% + increase in lumen output.