Lithium (LiFePO4) vs lead-acid — is it actually worth the upgrade?

Get this question on almost every power-system job. Real tradeoffs, no sales pitch:

Lithium pros: roughly 2x usable capacity per rated amp-hour (you can actually use 80-100% vs. ~50% on lead-acid before damaging the battery), way lighter, thousands of cycles vs. hundreds, faster charge acceptance.

Lithium cons: higher upfront cost, needs a battery management system (usually built-in on quality units), most chemistries don't like charging below freezing without a heating element or cutoff protection — matters if you're running cold-weather routes.

For anyone full-timing or boondocking regularly, the cycle life and usable capacity usually pay for the price difference over a few years. For occasional weekend use, lead-acid or AGM is often still the more practical call. What's your usage pattern look like?