I'm considering scratch building a couple of Centaurs for my small IG force. Looking at using them in a tallarn list, to carry a command squad and an officer.
Looking at their stats, compared to a sentinel:
Can carry a few guys
Weapon load-out is more consistent with number of shots
Tougher then both types of sentinels (more wounds, hire toughness, higher armor)
Shorter, so easier to hide behind hills and taller buildings.
No scout move
Not as good in melee despite double the attacks (not that sentinels are all that much better)
No AT weapons, or pintle options, only heavy stubbers and an H/K missile
Wider and longer, harder to hide behind narrow terrain. Might not fit through some openings compared to sentinels.
More expensive. Costs start to balance out after including heavy weapons on the sentinels.