I considered and looked at all three this past March when I decided to get a larger insert. What steered me against the Harman were a few things. The firebox, I really wanted to be able to load NS, which is not really possible with the Harman, though it does have andirons which makes EW loading less of a problem -- less risk of wood falling against the glass. But the firebox on the Harman is really the same as on their freestanding stove, which is a top loader, which would be ideal if the insert had that capability. As it is, loading the insert full looked like it would be a problem since there was a lot of capacity above where the door opening stopped, that area of course could be easily filled if it were a top loader.
The Harman was the one I really wanted. As their literature indicates and Seasoned Oak will attest, when you get it running right, the output is phenomenal -- very uniform and even heat level, but besides S Oak here, there don't seem to be a lot of boosters of the Harman and there have been a few who have had problems getting it running right. If you're someone who is very technical and methodical I would think you'd be one of the ones who'd get it working right.
Another negative was the cost of replacing the fragile refractory chamber, somewhere around $300 if that breaks or wears out and needs replacing.
I liked the Quadrafire until I realized those side bay windows do not have airwash and will blacken and need cleaning, if it bothers you when the windows get dirty. Some are not bothered by that, I would have been.
So it ended up between the Regency, the Osburn and the Summit. I preferred the blowers on the sides than under the ash lip, liked the look of a bayfront insert, and I really was not crazy about burn tubes and vermiculite baffles, which had been an issue for me with the Century. The Summit was the only one which had the features I preferred, and I like the look of it the best of those three, with the Regency coming in a close second. In fact, I almost bought a Regency floor model, until the dealer told me he he'd charge me a delivery fee, because he'd have to pay a bridge toll to cross from NJ into PA, so it turned out not to be such a good deal, and I got turned off by that dealer's attitude.
So of your three, I'd pick the Regency.
Edit: Oops, guess I didn't read carefully. You just got the Regency. I think it's a good one, well-made, and am sure you'll be happy with it.
