There's an option for a pop baffle between the horizontal and vertical chambers, which I have. The temp difference can be maybe 25 or so with it out and 50 or so with it in. This is measuring where the therm is, which is a good ways away from the firebox - it gets hotter if you go closer to the FB unless you have tuning plates.
For parties I'll usually use the vertical for holding or for things that can be brought up kinda slow like sausages or beans (placed under the sausages of course!). You can low smoke like around 150 for bacon or sausage while you smoke ribs or whatever in the vertical - I'll usually scoot over towards the firebox for a temp of around 250 or so, as my cooker has variance across the grate, which I very much like.
What's the story on that cooker in the pic? Gonna be yours?