I agree with Emperor Mollari regarding the rockets, using LHTR 2.0. With OOB Heavy bomber are more dangerous and useful also for “conventional” attacks.
For sure rockets are a more effective way to SBR. But Heavy bomber may be used also to support land unit attacks.
I think that the usefulness of a Weapon Developement is also related to the number of unit available that can benefit from the improvement and also the number of time that such units use the improvement.
Having super submarine and no submarine… is not so great. Similarly, having super submarine and no opponent ships … is no so useful.
But Funcioneta makes a good point: Russia and UK have slightly difficult to spare IPCs from production to be used in Weapons Development.