Joined the club, Rod pentode superhet radio.

[Mike Watterson]

A point I would make though is that rod pentodes were a clever design to circumvent some of the limitations of traditional valves. As such they will almost certainly have limitations in comparison, as well as their intended advantages.

I think it's because they didn't have Silicon till later and the RF performance of their Germanium transistors was rubbish at the time of the early 1j17b.
Another factor is that for MiGs and Satellite the Rod Pentodes are more robust to EMP from weapons or from Cosmic Rays. The Rod Pentodes were not better than mains valves the Russians had, but better than B7G miniature 1.4V valves (they did 1.2V variants of those for NiCd) and much better than the USA & UK wire-ended sub-miniature types. The later Rod Pentodes are also staggeringly economic giving better performance than 50mA 1.4V B7G types but at as low as 11mA and 1.2V NiCd supply.
They did use AF power Germanium for simple HT inverters for most of the Rod Pentode sets. Compare Ge transistors as inverters and audio out on 1950s valve car radios in the west.