Did you make a decision? I am not sure of the system you're referring to, but we put in a geothermal system and could tell you how that works, but I don't think it's the same as what you're asking about.

I did not make a decision yet. I don't think they are the same. What is geothermal heating? I cant decide if I should spend a lot more money for hot water radiators or the significantly less expensive forced air system.

That's a hard decision. I live in the southeast, so our winters are much milder and heating isn't as much of an issue as cooling which is why we don't have as many heating systems to choose from.
The geothermal is a forced air that uses a gel (can't remember if it's mixed with water or not). There is piping that is run in a loop through the yard underground. The earth acts to help warm or cool the gel and it's run through the system and heats and cools the air.

It sounds like a type of geothermal system using the natural heat of the earth to warm your air. But worth along HIM to explain it to you if he is the one trying to sell it!

What your contractor is describing is a boiler hooked to a fan/coil unit and ducting...pretty much the best of both worlds...and the most expensive. Unless the boiler does double duty as the water heater the redundancy of the two appliances is enough all by itself to send me in another direction. Geothermal heat requires land....or a seriously deep well. If your contractor is talking about wall or baseboard hot water heat units with a fan, it may not be acceptable in the summer either. New york summers get humid and hot and the relief of AC is something most homes cannot do without.

Is it the best of both worlds? I am concerned the air will be dry and Less energy efficient than radiators since no heat is being retained by the cast iron radiators. To the contrary the air system is 8 to 10 thousand dol cheaper.

I grew up with radiators and thought they were the ugliest things in the world. I couldn't wait to move out and into a "modern" house with forced air. Well, the first winter I was out of my parents house, I got sick every 2-3 weeks. When I lived with my folks and radiators, I would catch a cold once every 2-3 years.

Needless to say, my opinion of radiators quickly changed as I learned to live in a bunch of "modern" houses with forced air. I learned that if I dared turn on the heat,without first getting my room humidifiers out of the closets, filling them and turning them on, that I would be sick as a dog within 24 hours.

My advice? This is your home. Do it right the first time. It sounds to me like you know which way is right for you, but you're just hoping to hear that something has really changed in forced air. The worst thing to do is to pay for a fancy forced air system, only to regret it later. You may not want to pay more, but you won't regret paying for consistant, efficient radiant heat.