I have the Avery Mark III tagging gun for fine fabrics and I really LOVE it!
Before that, I had either the Collins or Dritz brand and the darn thing almost soured me on tagging guns forever. The needle jammed every time I tried to use it and the little key that holds the needle in place came out every chance it got.
I got the one for fine fabrics along with the tags and extra needles on eBay and it works great. I use the 1/4" long barbs/tags and I put the needle down through the quilt and back up to the top before I pull the trigger so that both ends of the barb are on the top side of the quilt.
The barbs hold better this way and they are easier to remove when you're quilting than when you just stab the needle down and pull the trigger.
This is the gun I bought - this seller also has large lots of 1/4" barbs.
http://cgi.ebay.com/ws/eBayISAPI.dll...m=260701109587
The one disadvantage to these finer barbs is that I can't find them in anything but clear. I would love to use red or orange - some color that would stand out on a quilt top.
I've sewn over quite a few of these things because they "hide," even when you rely on your sense of touch to see if you've gotten them all out of the way.
Fortunately, it doesn't hurt your machine when you sew over them - even the fine needles just punch right through them. They're realllllly a pain to get out when they're sewn in, though! :D