Obviously I have a bias but will try to keep it in check here
Cost - I expect that over the life of the stove that really won't make a huge difference. Both stoves should last 10+ years and as such $500 is at most $50/year difference which frankly shouldn't hurt too bad - then consider you get 30% of that back in tax rebate... so I wouldn't put a huge weight on that (although it is a nice thing of course, less up front money is always good).
Dealer vs direct - well, someone has to install it either way. I agree with Franks there, you should be able to tell the dealer "I just want the stove, here is the cash". However - think about the support of any issues or questions. Here I will tell you that Woodstock is extremely good. Best customer service experience I've had with any company in years. I have no reason to believe that they will go away - dealers to come and go, but given that WS has been there for a long time and are making an excellent product I don't see why they would disappear so I expect that support, if ever needed, to remain in place.
Stove quality - I can't really speak to any problems with the Heritage as frankly I expect the issues are few and far between. I always have thought of them as excellent quality stoves. I do know that the Fireview I have is quite a piece of quality work. Details of construction are nice - I don't see any excess sloppy cement etc. Having visited the factory I can see that the folks there take pride in their work. This is not to say other stove mfgrs are any less, I just don't know about them.
Complexity - This is where I will get a little bit defensive although I have not had the stove for very long. ANY stove if you leave the air open too long will result in an overfire and high flue temps. Yes, as others will verify, operating a CAT stove is slightly more complex than a non-cat stove. It has one more control lever on it and thus another step. However I can tell you now it is less complex than my previous VC non-cat stove! But to the comparison at hand it will be more complex, but will it be complex enough to cause you trouble? Somehow I doubt that is the case - bottom line I doubt that the Heritage is a "load the wood onto coals and walk away never to adjust the air or anything until next reload" perhaps it is - if so, I'll be corrected shortly by someone.
Now to the Cat - I think this is a difference that will make the most difference day in and day out. You will get amazing burn times and clean burns when dialed way down. I have only had the stove burning a few times (less than a dozen) and I can tell you it is incredible. I literally had coals after 21hrs the last time I burned yet no smoke for the burn - I had turned it way down since it got too hot in the house (shouldn't have burned that day.. too warm). The point being that I COULD turn it way down and extend the burn without smoke and result was a clean, loooong burn - not a sooted up chimney.
Both stoves are nice big rocks so will benefit from the thermal mass and thus keep the firebox hot. Both will also radiate out for hours after the burn and moderate the peaks of heating. Fireview will likely have fewer spikes in heat output just due to being able to dial down the air more and extend burns with the cat burning smoke off.
I don't know about the Heritage flue temps, but I will also comment that in operation the flue temps on the Fireview seem to be amazingly low. To me this translates into more heat staying in the house. Would be interesting if someone with a Heritage can post their flue temps - seems the FV will run 250-300 as a course of 'normal'.
Now to sit back and watch the fun