Tio, the first board you get will not be "THE ONE". You'll not win anything the first time over. Racing is fun, but we (I'm just starting riding these boards) have a lot of ground to cover to be competitive, so forget about getting a board that wins, and concentrate on getting a good first board. Think about what you want to achieve with it. What the conditions are around where you live.
What are your options and do you have a chance to rent them for a few days before actually buying?
I have only ridden the Naish Venturi ( I own this), a custom Amundson and a custom Augera boards, which I do not think are the same as the boards you are looking at.
Very different boards, and as is mentioned earlier in the thread..fins make a huge difference.
Anyhoo....make sure you don't are overambitious with the first board...the really hard core raceboards with huge fins are way harder to ride..big fins drive upwind better in light wind....on the other hand, don't get a raceboard with no / super small fins...then they ride like oversized surfboard, and are not as much fun IMO.
Ok on the 2 knot claim. Come on, you cannot even fly a kite in 2 knots. There is not enough lift.