I spent the money to get a dynamo (required a wheel rebuild) and then got a new bike a few months later (removing that hub and building a new wheel again).

It is 100% worth it to me as it gets rid of the worry of charging your lights and not having a charge. Also the Dynamo hubs have little drag and LED lighting these days. It makes your bike a worry free choice. You will not want to go back to rechargeables after using a good Dynamo hub.