Hi Screamer and Scotty,
C/W a real Lechner, I've no idea, as I never sailed one.
I'm 99% sure the same for Tiesda.
The wind range for the Serenity is more governed by water state (no, that is not dodging the question
) as in flatter or very short chop conditions, the Serenity is still actually pretty fun (if a bit challenging) in winds up to around 15 kts. Most guys would consider a reasonable limit is probably around a tru e 10-11 kts. Lower wind range is basically zero, although with obvious issues at that speed, however again on still and flat water, it's actually quite navagable with a reasonable pumping (maybe more fanning) technique- yes, it is slow in that mode, and yes current etc can have a significant effect also). Bigger issues are popping cammed sails etc in no knots
Running powered and broad with the centrefin(board) also takes a little getting used to, and maybe benefits at higher speeds from a slightly more assertive (or committed) style than typically "pleasurable" Serenity sailing is all about, but considering its nature, Serenity does get the job done a lot better than expected. Absolute dead downwind run is more challenging with any serious speed, the centrefin lift can get a bit much as the speed increases.
Upwind the angle is very good c/w FW or upwind short boards, however lacking the rear fin/centreboard combo (as per true DivII boards) the Serenity would not quite have the same upwind extreme as those old pure raceboards.
But remember, the magic of Serenity is a lot more than competition and being first or fastest. There is a huge element of satisfaction in just going out and relaxing on that board (something Serenity probably delivers even more than a classic DivII racer)- the performance factor on Serenity is as much in the pleasure of actually sailing it as any form of racing.
Yeah, I know, get a bunch of guys and board together and we have to have a race blah. But don't miss the point of this board, it's a cruiser, not a drag racer.
Cheers ~ Ian