Sorry – thats not that then!
Somewhere in the depths of memory is a statement that "a silver solder will have lost 50% of its tensile strength at 33% of its solidus temperature" Does 50% of a large number exceed your test pressures? I believe it does!
You have been using successfully, a very similar product, 455, for years! They both conform to ISO 17672 Ag155! Boilers have remained intact and will do so. The biggest factor regarding joint strengths is the model engineer in so far as he controls joint design, heating techniques, and application of flux and alloy.
When you switched from cadmium bearing silver solder there was no compromise on joint strength. Joints are as strong now as they ever have been.
There are differences between the two products;
an understanding by its supplier of the needs of the model engineer as conveyed in their literature.
the availability of the alloy, by the rod, in small quantities to suit the model engineer and with relevant information.
The support by its' supplier to the model engineer.
455 is the better product
Keith