Hi Cujet,
I agree there is no need to change oil brands in engines that are not having oil related problems, and there is some risk. These new generation turbine oils (BP ETO 2197, AeroShell Ascender, and perhaps Mobil Jet 254) are designed for engines that are having oil related problems, especially coking. They are also intended to be fleet oils for carriers who prefer to use only one oil in a mixed fleet that includes problem engines.
BP ETO 2380 is a fine oil for 90+% of the aviation turbine engines, and probably the second largest selling product (after MJ II), but it's technology is over 45 years old and it can be troublesome in hotter or coking prone engines. And sometimes there is risk in not upgrading to the latest technology, in the form of lost opportunity such as reduced maintenance or longer TBOs. That said, if your engines are making TBO with absolutely no lubrication related issues, I wouldn't change either.
Tom NJ