Over 25 years ago my wife and I build an oversized home and we had an instant water heater installed.
It did live up to its name we had instant hot water through the house, but we did run into one problem.
We had also installed a large tub that should had been listed as a small pool, by the time half of it was fill the water would turn cold.
Since I do not know the first thing about instant water heaters, I can't tell you if this is a problem with all instant hot water heaters or it was the way ours was installed.
But before you go forward with this find out if there is a capacity level.

Hot Shower as long as you like
 

It may take a while to get your hot water to your faucet, but once it’s there you can have as much as you want. Shower an hour, shower 5 minutes, it doesn’t matter

Tankless will not save you much money because the cost of keeping water hot in a hot water tank with newer models in Florida is minimal. Also the amount of money two people use to heat hot water per year is only a couple hundred dollars. Tankless is not worth the investment unless you are building in a new house.

Water Heater
 

I did some research regarding thankless, solar hybrid, and regular 50 gallon water heater. The cost benefit did not warrant the tankless heater or hybrid heater. So ... Mike Smith replaced our water heater with a new 50 gallon Rheme heater for $950 & took away the old one. We added a recirculating pump for about $450. That gives us hot water at all faucets within 4-5 seconds.

Do you mean Mike Scott Plumbing?

I used to have an 80 gal water heater. I put a timer on it so it heated from 5 AM to about 8 AM and from 5 PM to about 9 PM. It was great! Always had hot water while it turned on to heat up twice a day. I really miss having a timer.

Had an instant water heater. Hated it. 2 gallons of wasted water to reach the shower toward the back of a villa.

Now have a 40 gallon water tank in a second villa. Wish I had a timer on it. Thinking about getting quote on installation of one. Currently hot water reaches master shower in the back of the Villa within about 1 gallon of wasted water .

The standby losses are pretty easy to approximate. The losses are the surface area of the water heater (in sq. ft) times the temperature difference between the air outside the water heater and the water inside the water heater (in F) divided by the R-value of the water heater's insulation. This will yield BTUs/hr of heat loss.

As an example, let's assume the following:

Radius of water heater: 10 inches
Height of water heater: 50 inches
Water temperature: 120F
Air temperature: 75F
R-value of water heater's insulation: 16 (units are such to make the result come out in BTUs/hour)
BTUs per kWh: 3412
Cost of electricity: 13 cents per kWh

For this example, the standby losses should be on the order of about $24 per year.

I have already had a company refuse to quote since my tank water heater is over 12 years old.

We have Rinnai tankless hot water heaters in 2 homes in MA and absolutely plan to install one at our home in TV when the time comes! Very efficient, hot water on demand.

Not my experience with our Rinnai in MA- we’ve had 11 people in the home for a week 3 showers indoor plus an outdoor shower running and I can do dishes with hot water at the same time. No issues with it keeping up with demand.

I did it to make more space in the garage

We had a licensed plumber do some work for us and asked him about tankless. His response was I would not see the payback for at least 10 years. Take his comment for what it's worth.

Heat Pump Water Heater
 

Speaking of water heaters, has anyone installed a Heat Pump Water Heater? Pros / Cons?

I have thought about it. There are a few possible issues. The height of the unit may be a problem for some of the utility closets in the garages of homes in The Villages. If it can be installed in the utility closet in the garage, you will need to provide ventilation to the utility closet. Perhaps access to the hot air of the attic but there might be some fire code issues with that. The unit will produce condensate so you will need to tie into the condensate drain for your HVAC air handler - this shouldn't be a problem if the unit can be installed in the utility closet (where the air handler is located). There could be other issues.

There was no maintenance for 15 years on my water tank. They last and never thought twice about it in all those years sitting in the garage. I'm just now on my second one. Why would you want to trade that for a more expensive unit ($600 + more) that takes costly yearly maintenance for a box that heats water in your garage unless your planning on showcasing it when friends and family stop by.