First of all, I would like to thank you for your advice. I am learning a lot from your responses and suggestions. My larger sail in the mail and I am hoping that by the next season I will get a board that would help me progress. Here is another thing that is puzzling me...
I took my old board and sail out yesterday. At first the winds was kind of weak but later picked up a lot and experienced guys were zooming all over the place. I kept heading out and often felt that my 5.0m2 was on the verge of overpowering me. I noticed that the "pros" were using sails in the 5-6.5 range and 116-120L boards. The question is have, concerns the way wide boards handle waves, which were causing a lot of problems to me. Provided that I get a larger sail (8.5 or 9 and up) and GO 175 (or Rio M with board up) and a decent wind is blowing will these still pretty wide boards be able to cut through (or skim over) the waves while planning?
Also, is using larger sail in a light wind equivalent to using a smaller sail in a stronger wind or am I overlooking some basic understanding the science of windsurfing? I am asking that because the last time I sailed, I felt a LOT of lift coming from my sail, I was hanging on the boom on the windward side of the board but I felt like the board was holding back and pounding into the waves instead of sliding over them even though I was in the back of the board. I am sorry if any of this sounds stupid but I am trying to learn and understand.