Bigfred
I am not sure which type of polybutelene you have installed in your house, though the 2 manufacturers that spring to mind are Iplex (commonly known as Profit) and Hepworth H2O. I have installed many homes with both systems.
The Profit system uses a copper fitting incorporating a seal on the inner tubing using a copper crimping band.
The Hepworth H20 system seals using a rubber O-ring and stainless steel grab ring in a poly fitting. Hepworth has the longest warranty I know of in the industry, guaranteeing its product for 50 years. (Check with the manufacturer on conditions)
The main advantages a poly pipework system has over metalic systems is the elimination of water hammer.
Polybutylene and cross linked polyethylene systems have been tried and proven overseas for many years before they were introduced in Australia.
Hope this releives your distress and anxiety.
Regards
Damo