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It would be a fabrication to suggest that I was a particularly good badminton player - my knees are too creaky and I am too old and worn out to do more than enjoy playing on a friendly basis, though I do play every week. In spite of this lamentable lack of skill I do notice the difference between various brands of equipment, including shuttlecocks.
The cheaper brands tend to disintegrate quite quickly, and it is pointless playing with shuttles with missing feathers because they just don't fly straight (or as fast). I've discovered then that it worth paying a bit more, which is where these Carlton shuttles come in. At around £22 from our local shop, they are not all that cheap (you can get them for less online I suspect) - it comes to almost £2 per shuttle. However they do seem to last quite a bit longer than cheaper options, and importantly they retain their flight quality for a much greater proportion of their life time.
A new shuttlecock is a joy to use, there is a zing as you hit them, they fly fast and true, and it makes for a much better game as good shots are rewarded and poor shots more easily punished. These Carlton goosefeather shuttles keep these characteristics for a reasonable length of time. Cheap ones scarcely last a game sometimes without losing feathers, or becoming noticeably slower or out of shape, these can last a whole session and still be quite decent. To start with they fly comparably, so aren't intrinsically any faster, but are more robust (though if you unluckily hit them wrongly they break just like every other sort). I would say they are about average for speed, and work well with a mixed group of players (like who I play with - men and women of different sizes, shapes and strengths).
Overall, I've found it's worth paying a bit extra for better quality shuttles, and these are amongst the best I've used, and are very suitable for our group.