Fundamental flaws in your plan.
1. Questing and Raiding are two very different aspects of the game. While your questing you care about efficiently completing objectives in as least time possible. While raiding, you care about encounter mechanics and how to overcome them.
2. QuestHelper type addons are generally the most expensive addons on system resources. Running these addons while raiding could cause a decrease in your system performance. Raid encounters themselves are significantly more elaborate than the random quest mob you see around the world which is why system performance tends to naturally degrade some in a raiding environment.
Bottom line, you are going to have to log out, and change which addons you are running when you switch between these. Particularly in the case of running questing addons in a raid context. Running raiding addons while questing will have significantly less impact since they generally don't have as large of a footprint on your system. Unless you have an insanely decked out system, you're just wasting system resources if you're running quest addons in a raid causing increased loading times and reduced system performance.