Plumbing & Ducting

Chris the plumber has been putting pipes everywhere, Dave the ducter has been putting ducts everywhere, and although in an ideal world ne'er the twain shall meet, meet they did. However, they worked it out. Chris doesn't love the access joist system as much as the duct man does, however, as his pipes are rigid and the 7.25" clear it gives him isn't quite enough without some tweaks, but he's coping.

I have been getting educated on choices. Valve choices, fixture choices, faucet choices, hot water heating, you name it. Please respond with names and information on on-demand hot water heaters (your likes and dislikes please) under comments; I will need to make a decision on this soon and welcome any opinions, pro and con.