My full int warlock is wearing full solmiki cloth (t10) and with squire food buffs i have like 72k hp. I don’t think you really need more hp than that unless your party isn’t static with a reliable healer and support (which is pretty much linker3 and kab3: pretty standard). Of course, it also depends on what your armor is. Even wearing cloth, I think i have over 10k physical defense so I’m pretty safe from most attacks. In fact with Lifeline and Einsof with SP attribute, I have over 400k hp and don’t even need to bother dodging attacks.
If your hp is that low, that means you have almost no CON on your equipment either, which means that healing effects affect you very little. Mass heal will heal only 1/4-1/3 of your hp and you will have to step on a lot of heal tiles to get all of your hp back (this also is a detriment to your party since if you eat all heal tiles, there’s none left for anyone else). Con greatly increases the amount you get healed, so yes it’s a great stat if necessary. After the future cleric rework, healing will be based little to not at all? on your CON stat (actually it’s the HP recovery you get from con) and mostly on the cleric’s SPR and their healing power.
Basically final answer is full con as a dps in pve is the my-armor-is-crap choice.