This is not about the games compatibility of HDLoader/HDAdvance but about how well HDLoader and HDAdvance can actually coexist if used at the same time.
I started of using HDLoader but got HDAdvance soon after that. Now I'm still uncertain about their advantages/disadvantages. I heard they are pretty much the same product with the same compatibility of games and so on, but how do they get along with each other if used in a boot selection menu like PS2Keylauncher? Do they use different partition names/modes and/or configuration files? Is it dangerous to boot/run games with HDAdvance if all your games were copied to HD using HDLoader?