Randy, burning VF logs is not a guarantee you'll have problems. However, statistically, they do carry a higher rate of certain complaints than their vented cousins. These complaints include: odors, excessive heat for the space, humidity, odors, frequent dropout of ODS pilot due to lack of simple maintenance, odors, lack of realistic burn, odors, damage to fireplace headers and mantels, odors and more. Did I say odors? THEY STINK! I can smell a VF burning the moment I walk into a home. I have never walked into a house with a VF burning that I failed to smell it as I entered the home.
You mentioned no problems with CO2: are you referring to the amount of CO2 you and your family exhale in any given day or from combustion spillage as CO2 displaces O2 which can lead to CO production? Do you have some sort of carbon MONOXIDE alarm or monitor? FYI, it is CO that is the deadly poison-not CO2.
You mentioned no problems with sooting: have you had a professional take lab samples and have them analyzed? If not, then I can assure you, you do not know that you don't have sooting issues.
Be advised, there isn't a single building scientist or industrial hygienist out there who is willing to publicly endorse any sort of VF appliance in a building. Moreover, if you have an energy audit done and want to claim a tax credit, they are required to remove any VF appliances from the home. Doesn't that tell you something right there?
Why do you think the largest fireplace company in the world turned their back on the VF business? Because the cons outweighed the pros.
If you read the 2009 IRC, you'll see there are very few applications where you can legally install VF logs in most houses, esp. once they have been weatherized.
VF logs are not intended or tested as a primary heat source and should not be run continuously for more than 4 hours regardless of home construction or mechanical systems. Moreover, the last thing you want to do is blow large volumes of air around VF logs. Stay air currents can cool the flames or cause flame impingement, which leads to sooting, CO and odors.
If you're hell bent on burning them, do yourself a favor and get an unlisted low level CO monitor--not a UL listed POS alarm.
BTW, we call VF logs "lung vented"--think about it.
PS-- VF logs stink!