Can you please let us know what the issue is that you had with the duotights? We generally get very good feedback from people using the duotights. From our experience the most likely cause of leaks is:
1. The line is not completely inserted into the fitting. You have to push with significant force to make sure the line is pushed all the way so both o-rings are being used. For the 8mm duotight fittings for instance they should push into the fitting 15mm so both o-rings are sealing. If you are unsure what you can mark the beer line with a permanent marker then ensure the hose is pushed in up to this permanent marker line.
2. Ensure you have a clean cut. If you have difficulties with this then get this too:
Tube Cutter - Pipe Cutter - 2 in 1 for EVABarrier, PEX, HDPE, Vinyl Tubing
3. Line specification
Make sure you are using
Evabarrier tubing or another tubing with good tolerance on the diameter. If the diameter is out by more than 0.15mm this will reduce the reliability of the connection.
Also with regards to the barbs we do sell these barbs separately if you really want to use the barb on our regulators:
Swivel Nut & Barb for MFL Thread Disconnect