Clearly the problem isn’t the heating system. 
Writing as a person who has built many homes, including high end specs, and worked with quite a few architects, and is a member of the not so noble profession of real estate brokers, I’m with @BunsenBurner on this one. Most realtors and architects know next to nothing about these systems, and most contractors will recommend you do whatever they’re in the habit of doing or what’s most profitable for them.
I actually think the feedback here is very informative. Although I disagree with a lot of the opinions I’m reading here, they do reflect people’s perceptions, which is what @BunsenBurner wanted.
It comes down to the different types of opinions one is seeking. Someone like me, who has owned such a system, would be very comfortable with one, others not so much. But those opinions matter too, for resale.
“You haven’t met my husband, who likes to turn the thermostat 5-10 degrees colder than I can tolerate. We have endless battles over the thermostat. If I had to wait an hour for the house to warm up, I’d be really, really cranky.”
This is the prime example of an insight I would never get from a realtor or builder. It would have never dawned on me that thermal inertia would cause issues - Mr. and I are always in agreement that 68 degrees during the day and 61 at night are the comfortable temps during the heating season. 
^ I know several families who have thermostat fights!
How long would it take for the temperature of your proposed house to go from 68 to 61? And 68 to 61?
I seriously have no idea… It happens while we are either at work or falling asleep. If the bedrooms are on a separate heating zones, the bedroom temp can be set so it gradually cools down while we are inhabiting the great room.
I’m from the Northeast. I’ve always had basements. If I were moving, and I was deciding between 2 houses where everything else was equal except a basement, I’d go with the house with the basement.
We once installed radiant heat in a room over a garage. It warmed up the space quite well - I loved it. I would love to have it in my bathroom. I hate cold bathroom floors.
My inlaws love in northern Maine…house built on a slab…full radiant heat. It is terrific. Very even heat, and always comfortable.
I would love to,have it!
In Southern California there is a new trend towards electric radiant heat wiring under tile in the bathrooms only. It’s considered an extravagance in high end homes. No hot water pipe systems. That would be a recipe for disaster in my mind as a buyer, even though I have no specific knowledge about them. It would just make me start thinking of everything that could go wrong.
I grew up in a house with that, @coralbrook (we didn’t own it) and it was great.
@BunsenBurner wrote
I’d be a popsicle! I keep the house at 72-73 in the winter, H likes it at 68.
However in the summer I can keep the house at 77-79 and be perfectly fine. H comes home and cranks it to 74 and I’m like, brrrrr! To be fair, he’s sort of a slave to what his office keeps the thermostat at, and he’s conditioned to it.
His home office is in the basement, and he keeps it how he likes it. The battles only occur when he ventures upstairs and tries to mess with my level. I’m like, I’m not painting in a parka, back off.
Basements are big in the southeast because it’s the safest place to be in a tornado, which are fairly common around here. Luckily Seattle doesn’t have to worry about that, but possibly with earthquakes an in-floor heating system might experience cracking issues?
In that case radiant heat might not be the best option for you.
The idea is to have the bedrooms on the second floor, serviced by a mini split, so every bedroom temp can be adjusted separately. We keep the bedroom
window just a bit open when we sleep so there is a quick way to lower the temperature.
Yes…I would buy a house with radiant heat built on a slab.
They used radiant heat back in the 50’s in places like Levittown on Long Island, the houses were built on slabs and it was a lot easier than laying in hot water baseboard. The systems weren’t very reliable from what I understand and a lot of people replaced them.
That said, the modern systems are pretty reliable and efficient, so if it was a modern one I wouldn’t shy away from it. One of the problems with slabs is that areas on them tend to be colder than the rest of the house, my house is a split that has a ground level area off the garage on a slab, and no matter what I do it is significantly colder (my house is forced hot air). I looked into potentially getting a supplemental radiant heat system for that area, but it would have been expensive to implement (one of the systems was interesting, it actually circulated hot water from the hot water heater).
They are slow to heat up, that is one of their negatives, so if you step back your thermostat you may want to program it to come on earlier than you would with a forced air or hot water.
With that clarification it seems you’ve come up with an excellent solution for your needs.
HI houses rarely have basements or any heat. Many of them are built directly on concrete slabs. Eliminating a house because it’s built on s slab or doesn’t have a basement would eliminate our home and the homes of all my extended family, as well as our neighborhoods.
H loved radiant heat when he was in SKorea!