One piece fans when someone immune to blunt attacks creates ballon to absorb blunt attack tanks a blunt attack:
I would've agreed if it was just that.
G5 has high blunt force resistance even to haki attacks.
However, the issue is that Luffy didn't even comment on the heat......
Contrast that to magma-esque flames from Luffy, which would melt off Luffy if not for advanced conqueror's/armament haki barrier.
For a long time, Sanji fans claimed IJ flames > magma-esque flames, even though Oda considers magma as the peak of heat based abilities (and hence the reason why he compares flames he wants to hype by comparing them to magma)
At least we can now say that magma-esque flames are significantly superior compared to IJ.
It's ok though.
Sanji will eventually get magma-esque flames or something more superior/unique like black flames/amaterasu