Lithium will be much lighter, and hold a charge longer. There is no slow discharge (flickering, dimming, loss of sensitivity) with lithium batteries, when they die, they just shut off, hence why they “last longer”. That being said, if you don’t mind the weight, $20 for a new lead battery would work just fine. I recently replaced mine and I have no issues fishing 8-10 hours on one charge. I recharge every night I get home though. Additionally, you have to pay extra for a special charger… There are benefits, but in my opinion, for a flasher, I don’t see enough upside to justify the price tag.