Most players of Axis and Allies understand intuitively that the original heavy bombers tech "unbalances" the game by being disproportionately good. My own research confirms this by valuing the two additional rolls as 30 IPCs (per bomber), meaning that the tech pays for its 30 IPC research costs in one turn.

Some players allow heavy bombers only two rolls instead of three. You basically get two bombers for the price of one, +15 IPCs. That's still higher than other techs (6-10 IPCs), but less of an outlier than before.

My own preference is for a 50% increment in the bomber's original powers. That is two rolls for heavy bombers but only THREE numbers hit (instead of four), six numbers instead of four or eight. For strategic bombing, take the die roll +2 for a range of 3-8 instead of 1-6 (average of 5.5 hits instead of 3.5). This gives heavy bombers an incremental value of about 8, squarely in line with other techs'.

Is there a heavy bomber tech, either the "two roll" rule, or my 50% increment version, or some other suggestion that allows people to use heavy bombers without throwing the game out of whack?