Help Buying a Pellet Insert - Advice please? ENV Empress vs Castile

Long, long time wood burner. Took out a wood stove in the main house section and inserted a Napolean propane fireplace insert.
Looks nice, works fine, heats lousy. Central heat is oil so of course at $5 + a gall I'm going back.
Have a VC free standing wood stove in my den and is fine!
So with all the research - pellets here I come. ( Of course the earliest date for delivery is now November 08._
Question - have app 700sq feet of space that open cathederal ceiling to upstairs. So I figure 1500 sq ft.

I want to use this as a primary heat source and rely on the oil burner for backup. House 30 yrs. well insulated, new windows, etc.
This should be very, very cost effective.

I like the Enviro Empress and or the Castile insert. 30,000btu
Looked at the Breckwells. - asthetically don't like but are available.

Advice
1. Large enough to heat a living room/kitchen area with catherderal ceiling?
2. Venting. Dealer states I don't need a second pipe for outside air intake like propane. Aren't I using warm room air up then?

thanks - have to buy in a few days becAUSE PEOPLE ARE GOING MAD TO REPLACE OIL HEAT.!!
TNX

I can't speak on your 2 selections but I have a Whitfield Profile 30 that has worked real well for us last year. Check it out if its available. I think it would easily heat what you have described depending on the footage. We also have no fresh air intake and have no issues with that. Greg

Go with the shop with the best service if you do not pick the castile.