I've tried them Riaz, I had some I bought in Europe a long time ago. They are quite tricky to use since the bait has to be completely dry or else the bag will disolve in your hands.
I think it's a better idea to use an open ended feeder or use a spod to deliver the groundbait in a concentrated area.
More details about spodding can be found here,
http://www.fishingmagic.com/news/articl ... 6206899518
http://www.northwestcarp.co.uk/Carp-Art ... Guide.html
The spod can be made easily here using PVC pipe and thick plastic sheets for the fins.
Hope this helps