I have used Chipex and the colour match was very good. That said it requires real skill to get the repair level with the surrounding paint or the repair remains visible.
You wouldn't think of it to look at my poxy old wings, spattered as they are with stone chips, cracked filler, and general nastiness, but I have got excellent results in the past with Chipex kits by adding a wet-sanding step using 1200 and 2000grit wet and dry, followed by some vigorous polishing.
As Howard says, it's flippin' difficult to get the repair level the way the instructions tell you, but add in a judicious bit of rubbing down after you've filled the chip and it becomes a lot easier to get a great looking result.
