Pacific Energy D1 vs. Regency I2400

Would anyone care to help me choose between a Pacific Energy D1 insert and a Regency I2400 insert? I already own one Regency I2400 on my main floor and I want to add a second insert in the basement for the cold days when one stove can't keep up. I'm concerned that the Pacific Energy D1 has both a smaller firebox and a lower efficiency rating than the Regency I2400. The numbers are these:

Pacific Energy D1
1.98 cu foot firebox
69.3% efficiency

Regency I2400
2.3 cu foot firebox
77% efficiency

So the Pacific Energy D1 has a a firebox that's about 15% smaller. Combine that with the approximately 8% lower efficiency and it seems, based on the numbers, that the Regency I2400 should be able to put out almost 23% more heat per load of wood. That seems like a significant difference to me. What do you think? Has anyone had an opportunity to do a direct comparison of these two stoves? Obviously, the fact that I want a second stove means that I can't get enough heat from the first one so I'd like to get the most powerful stove I can fit this time. Especially for overnight burns, where you want to get as much heat as you can from one full load while you're sleeping, the Regency I2400 seems to have an important advantage.

I wouldn't think the EPA would let you sell a stove you've changed since you passed your emissions test -- your changes could have made things worse.