It also depends on the evaporation rate you are looking to get and how many taps you are doing; for example, I have a 2x8 evaporator and can achieve 45 gph constantly, sometimes more, sometimes less, depending on draft, wood, depth of the pans etc. If you let us know how many taps you are doing and what evaporation rate you are looking to achieve we might be able to save you some time and money. And yes you always need a flat pan connected with a flue pan or you are running a much higher risk of scorching the flues and burning the setup, and you can get much closer to the finished product on a flat pan. And with any flue pan, you will want a float, it will make life a lot easier and stress free once you get a good boil going and need to walk away for a minute it will always maintain a constant level in the pan. Best of luck.
2,000+ taps and growing
3'x12' Vortex, MAX flue, and steamaway
24'x48' timber frame sugarhouse