Therr is no intergration between the slow smoker and the time/temp on the "oven". Therefore if you set the time and temp the slow smoker is not set so it will continue to smoke and the burner still producing heat.  This eliminates the thought of set it and forget it.
The slow smoker does not fit very well against the SMOKER.  You will have to really overtighten it for a firm fit OR you will lose smoker around the insert.
You will NOT get anywhere near 6 hours of smoke...maybe 90 minutes.
Since you have 2 burners going the original burner's functionality is questionable.
If both the original chip tray and the slow smoker chip shute are smoker to you run the risk of turning you cook into wood tasting meat?
The unit does smoke but other written concerns are also valid.