Why do you assume that back blows would not have been just as effective at removing the blockage? Obviously in your case it's great that the Heimlich worked, and natural that you appreciate it having been used. In some cases though, perhaps back blows are even more effective. And they are certainly easier to perform correctly.
Also, five back blows take less than five seconds to administer. Certainly it is beneficial to know the Heimlich as well, and be ready to administer it if the back blows fail, but I'm inclined to agree with the current medical opinion that they should be attempted first.
I guess that given the sense of urgency I felt, I wanted to get the person breathing as soon as possible, and I knew from my personal experience that the HM was very effective.
I've also read that back blows may further lodge the blockage in the throat, especially if you can't get the person to lean over, and this was a concern for me as well. Whether it's true or not is hard to know, but when your family member is choking and close to losing consciousness, you really don't care about breaking ribs! It's kinda the same with CPR - you don't care about breaking ribs, and it's pretty common for that to happen during compressions.
I'd be interested to know what the potential injuries are from the HM - is the main one breaking ribs?
Yes, it's unfortunate that it is really difficult to formally study something like this. You can't very well induce choking to test the options.
My completely uninformed guess is that the 'further lodge the blockage' thing might be a result of the marketing campaign ("death blows", etc.) rather than an established fact. In that case, although it would take a few extra seconds, I can see it making sense to try back blows before the HM. For one thing, you may actually dislodge the blockage more quickly. (Especially, one would think, in cases that make the HM difficult, such as with pregnant women, or even if it's just physically difficult to get into the correct position due to surroundings.) And while of course I agree with you that a few broken ribs is an easy trade for continued breathing, I expect in rare cases those abdominal injuries could have serious (or even fatal) consequences. Ah, yes; a quick search came up with this[1].
Also, five back blows take less than five seconds to administer. Certainly it is beneficial to know the Heimlich as well, and be ready to administer it if the back blows fail, but I'm inclined to agree with the current medical opinion that they should be attempted first.