One of the many, many things that make heart pendants overpowered is that they carry less restrictions than other trinkets. Damage caps out at full chaos + sword damage trinket. ASI caps out at full vog + sword ASI trinket. CTR caps out at full Chaos + level 10 weapon.
Hearts don't have a hard cap like that. Why is that?
My suggestion is this:
Penta-heart gives 5 pips, since it isn't called hexa-heart.
Heart bonus supplied by gear caps out at 15. 5 from helmet, 5 from armour, 5 from additional pendant.
Lockdown class bonuses and vitapods are not affected by this limit, not unlike damage bonuses from sprite skills, sparks and such.
If you limit the health boost like that then what about armors that give more than +5 per piece? I think it is fine the way it is now, because it makes UVs more valuable. If you have an ASI UV on your weapon, you might be able to use a health trinket instead of a ASI trinket, which makes your gear stronger than other players' gear. But if health is capped, you'll have a free trinket slot anyway so you dont need the ASI UV.