u can upgrade your surefire on ebay for about $35. cree R5/Q5/P4 drop in ($13 shipped), crenelated clicky tail cap ($12 shipped), crenelated strike bezel ($10 shipped)
the cree R5 has different modes/brightnesses (low-mid-high-strobe-SOS)
i bought the solarforce clicky tail cap and strike bezel and am VERY impressed. waterproof, clear glass, durable, no cons i can see. yea it's chinese, but $12 versus $50 seals the deal for the US made surefire accessories. i couldn't justify paying more for a tail cap than i did for the flashlight, personally. YMMV
edit:
the chinese stuff is made from a very sturdy aluminum, but aluminum is a soft metal. i would say if your life depends on the light, then the surefire stuff is probably worth the extra dough. for me, i built the flashlight for all around use not war or patrol so it works great for me. hope this helps qualify my post above.