I started a GreatPlane Ultimate 40 last week. The build is very straight forward,but you have to build 2 wings, and wings take time. Also setting up a Bipe is harder than a single wing, because of setting up the incadence on both wings.
I would recommend going with the 4 Star. Great kit and easy to build. Then if your not burned out with building ,tackle the Bipe.
When you do start building ,make sure you have a good flat building board. I use a 2ft by4ft 3/4in. piece of particale board shelving, then screw a 1/2 piece of sheetrock to it, then check the surface with a 4 ft straight edge to make sure it is truly flat. Some guys use acoustic ceiling tiles. but they don`t hold the T pins as well. I have used both, and if you make sure your surface is flat, both well work fine.