Here is a link to my water tank repair -
Do I Dare?
Two and a half years later, up to Alaska and back, the tank does not leak. I had all the tools (Soldering iron) and materials. Since my tank is an in floor the replacement cost was somewhere around $350 plus shipping I decided to try the reapair.
I'd go for repairing with a plastic welder or your soldering iron over repalcement. If it does not work, you are in the same place you started. My 36 year old tank is still flexible and does not exhibit signs of becoming brittle.