Hey bene
There's a whole lot of things that could be debated here...tail shape and fins is a major contributor to this concept!
A thruster will tack up wind however a quad will this better and tack upwind with ease due to the tracking of the fins :) they lock in and won't release as easily! Also tail width and shape plays a contribution as a wider tail may also release due to increased flotation and area! I've found that a rounded square tail or slight swallow tacks upwind nicely personal preference and for down the line a rounded pin tail or narrow round tail works well in fast down the line riding...
Getting up wind is also a factor that your kite plays a big part! If its a kite that can sit further to the edge of the window like a delta c it will allow for tacking upwind to be easier :)
Hope that helps...
Nathan