HVAC help please!

[steve.lim.dds]

Hi there. just an average joe homeowner with no hvac knowledge here.
I've currently purchased a home where its primary heating is through an infloor hydronic heating system. The infloor heating system is rigged with poly B (which extends into the 2nd floor, 1st, basement). the house already has existing ductwork for AC (which is roughed in but doesn't have any AC installed). I'm hoping to completely ditch the hydronic heating system and switch to forced air heating.
So far, I've had two HVAC guys come and take a look to give me a quote. Both agreed that there are enough registers in the 1st and 2nd floor. However, first guy said there aren't enough registers in the basement, and it'll have to be roughed in. Second guy said there are enough registers in the basement and it is not needed. I'm hoping to have a 3rd set of eyes but that wont be until mid July.
Any advice on how to tell how many registers id need to have enough heat in the basement? Should I just get another HVAC company to come and have a look or would I need to get a mechanical engineer for a proper assessment? (PS: I noticed that one of the two bedrooms and a bathroom doesn't have any registers)

[samihabib]

The basement if finished or has rooms, during the winter will be much colder to live in. Unless you have a fireplace to reduce the cold feeling you're gonna need to have registers.

[Sergroum]

I lost count to how many instances I've encountered when people finished their basement with insufficient registers and rented it out.

The result is that the renters are forced to use electric heaters which probably ends up costing the house owners many times more moolah then if they ran the registers. Also a source of great discord between landlord/tenant blah blah.

Conclusion.  Please make sure you've got appropriate supply in your basement. It'll save you a lot of stress.

[rmuntz]

If the in floor is working properly, I'm not sure why you would ditch it. In floor is wonderful heat.

Maybe ditch the ductwork and install a few ductless splits in the areas you want cooled.