45 ACP is more powerful than 9x19mm. This may make a difference in a shot you have to take, but it may not matter either. Jello testing is for comparative purposes and does not duplicate real life damage. It's a tool to help you make a decision. Remember, the bullets are tuned to expand within a certain velocity window. The odds of expansion decrease as friction decreases velocity over distance. Once they start expanding, then they're going to lose velocity and stop. The wound channels may or may not be of the same length and there is no guarantee of expansion. It is hard to determine odds. For example, maybe the 9mm won't make it to the heart through the arm, but the 45 will, or vice-versa. Again, nothing is concrete.
Since you're likely talking about a Browning Hi-Power versus a 1911, reliability is paramount. I have found the Hi Power to be far more reliable than any of my expensive 1911's. Therefore, if this is the case, I'd still choose the 9mm Hi Power over the 1911 in 45 ACP. If it were a choice between a SIG P220 SAO and a Hi Power, I'd just buy and carry both.