The bonding process of making bullets also softens the jackets some, so I had the same idea.

A softer jacket will obdurate more and seal the bore better (in theory) and yet bonded bullet hold together and penetrate well. I may need to buy some and try them next. I guess just for the fun of doing the experiment however.
When I look at the real-world, a 180 gr Core-Lokt Remington bullet is overall a good one, and holds together better than many standard bullets. It gets good reports on game as a rule, and I have use them for many years on deer and elk from 300 Savage, 30-06s, 308s and 30-40 Krag and never really had one fail me. I have only ever seen one come apart, and that one had it's core and jacket only 2" apart from each other. That was after it went through about 30" or elk. So I can't say it was all that bad. Most times you get either the picture perfect mushroom or an exit.

As far as the gas-seal goes, I wonder if it would matter. I don't have the super good vision I did for the 1st 50 years of my life, and a 1-3/4" group is as good as I can shoot open irons anymore, so if the the bonded bullet was more accurate I doubt I could prove it now. I have about 900 of the 180 grain Core-Lokts on my shelf. I might be smarter to just quit here and use this load for everything.

I am in my 60s now and I do not think I am going to kill 900 more big game animals in my life ------ let alone kill them all with one iron sighted Lee rifle.