Questions about a new propane heater.

Hi all,
Thanks for having me and I hope I can contribute something to your forum.
I'm about to purchase a new propane heater for my 16x32' inground pool. It will replace a 25 year old Laars Teledyne 250 that has finally expired.
I'm looking at a Hayward H200P1 Millivolt and have a couple of questions...
1. I'm at 3100' elevation. Is it really necessary to have high altitude jets? One supplier suggests it is and another says, at this level, it's not necessary. i don't know if the Laars had them.
2. Is there an advantage/disadvantage to going millivolt vs electric? I have a power switch for the pump close to the heater. My Laars was a millivolt.
3. My heat requirement calculations bring me to the 200,000 btu model and the 250,000 btu model is almost the same price. Are there energy savings with one or the other? ( I also have a supplemental solar system)
4. Where are Hayward heaters made? I'm in Canada and will be buying in Montana, so if they're made in North America, I won't have to pay duty.

Thanks for your help.
Scott

I bit the bullet and bought a Hayward Hayward H200FDP Low NOx unit. The fan eliminates the need for re jetting until something like 7500 ft. No duty, either.