I don't remember if state is the same as ao smith. I know last time I checked, there were only 3 manufactures anymore. just named differently.
for smaller size, we have 5 people in the house and a 50 gallon works fine for us. so you could down size and save a few bucks and be fine I think.
as for tankless, the pay off vs cost wasn't worth it for the size I needed for my house.
tankless works on differential temps. some go higher than others, but need even more gas or power to do it. so you have to know your coldest water temps and how much a tankless can heat it up based on gpm flow through the unit.
not sure on electrical how bad it is, but for me, I had to get a larger gas line to the house. so it made it cost prohibitive.
it was going to be 3 times as much for the tankless unit itself then a replacement hot water heater, plus another 1500 to run a new gas line.
While I am all for them, you pretty much have to plan the house for it, rather then retro fit for cost effectiveness.
unless payback in savings isn't an issue for you, and you just like to have "infinite" hot water.