Money pit? Here's the annual maintenance required:
There are also other videos that's about 8-10 mins that details in length about the hardest part, which is running the vinegar/descaler thru an external recirculation pump
As I mentioned in my previous post, only you can determine if there is any value in not running out of hot water or worrying about a leaking tank. If it has never happened to you, then there is no value and not worth the premium.