Surely your LBS would let you try before you buy?
Rather than spending all your wad on the brightest handlebar light, if money is tight, go for a cheaper handlebar light and a decent helmet mounted light like an Exposure Joystick so that you can see more than just where your bars are pointing. This is useful when going round tight corners, over brows, or just fixing punctures!
I’m not a rep but I love the Exposure lights and the fact that they are cable free. I’ve got an Enduro (now called a Toro) and a Jpoysick and ride all winter. Because they are cable free, you can use them as torches – you can buy a headband and use the Joystick for night running.