Well, has your existing HWH served you well??? If so, personally, I'd stick w/the brand. Other than that, perhaps someone else has a specific recommendation ...
RE: tankless units - Yes, they're fine for the home. Europeans have been using them for many, MANY years w/great success. You can search the WEB for Tankless Hot Water Systems. And if you're 'lucky' enough, Brian 'Tankless' Wood will post here and offer his assistance. He's the resident 'expert' on the subject (by my standards only.)
My best to ya and hope this helps.
Jay J -Moderator
PS: 80 gallon system for a home??? Yea, I guess, BUT if you have multiple showers/baths, perhaps 'splitting off' the bathroom(s) that aren't used that much onto a tankless system, and going w/a 40 gallon unit for the bathrooms that ARE used a lot. If you go tankless in ANY respect, be sure you have an Installer that's familiar with installing and 'sizing' these types of units. (You'll have to live with the 'results' forever ...)