From HistoryNet: Over 29 thousand B-29 air crewmen saved because they could land on Iwo. Some 7000 lost taking Iwo.
So I guess the answer is yes it was worth it.
Well, of course it was worth it except to the families of the Marines who perished.
But it still would have been better to build fixed bases in Siberia and defend them, rather than fight for islands. Stalin's excuse was that he had a fragile neutrality treaty with Japan that he didn't want to violate. He was concerned that Japanese troops would invade from Manchuria.
But Japan was already over-extended once the Americans entered the war. By 1943 Japan could not have sustained an effective invasion of Siberia; besides, it's not like Siberia is easy territory to conquer anyway. All we had to do was put the air bases a few hundred miles from the border and dare the Japanese to try to invade from Manchuria.
As for "29,000 B-29 crewmen" I think you need to check your facts and your math. A total of 3,000 B-29s were built over the lifetime of the aircraft but only 165 were operational by April 1944 and probably less than 1500 by August 1945 when the bomb was dropped on Japan. I can't easily find month by month statistics but we can make an assumption that 1000 were deployed to the Pacific by the end of the war. This is supported by the fact that the largest B-29 bombing run during the war was only 334 aircraft.
Assuming the loss rate was 25% for these 1,000, and that half of those landed on Iwo instead of putting down in the water, than means 125 aircraft were saved. That's 1250 men, not 29,000.
Even History.net says that there were only "hundreds of emergency landings on Iwo." Let's assume 500. Let's also assume that only half really required the Iwo landing, and half could have made it further to another base. 250 aircraft x 10 men equals 2,500. Certainly not 29,000. And that's not necessarily "lives saved" but merely lives that didn't have to be pulled out of the water.
Bravo to you for trying, but your math really needs some work. And when you make a claim you ought to give it a sanity check.
The B-29’s flying from Tinian, put Iwo on a direct line to Tokyo. Its location allowed P-51’s to fly escort, so the lives saved were much greater than the hundreds that had a place to land. Maybe that is how the estimate of 29,000 arose?