I won't answer your question directly, PL, but will provide some info. Thanks for the link.
Newer is a relative term. The RDR-4B is RDR-4A with forward looking windshear circuitry added in about 1995. The 4A went into service in 1982 on the new 767. That's 27 years, which was well before the FO on that flight was born.
It doesn't matter which WX radar; if the pilots don't get trained, they won't use it correctly. I have never known any airline to provide more than laughable WXR training, other than United A/L. It's criminal.
The accident report spelled out the major operational differences between the old magnetron radar and Arinc 700 radar (RDR-4, WXR-700). But the pilots weren't trained on the old radar, either. Further, the report didn't mention the shortcoming of the RDR-4 having a single tilt control, yet with split ranges available. The WXR-700 has full dual tilt, mode and range available. At altitude, to use split ranges adequately, you need split tilts.
AF-447 had WXR-700, but pilots apparently untrained in its use, from what I read on that thread. Has AF done anything about that?
The state of the art WX radar is the Collins WXR-2100 (and HNWL equiv), which provides automatic mode, tilt and range, reducing pilot workload, and ostensibly reducing the amount of pilot training needed. AF could have bought that radar when the 447 ship was delivered new, or could have retrofit the fleet at any time.
Some airliners continue flying Grandpa's radar, because the authorities lack incentive to require upgrades.
GB