Hi Obelix, there are so many spots to sail down the D'Entrecasteaux Channel and Huon River area and many look great, but there are very few people down that way who windsurf, so you rarely see anyone out down there.
As far as the Huon River is concerned, I drive down along the River to a place called Hideaway Bay (out near Huon Island) for work most days and the wind is often excellent, but I've only sailed out there a few times. Of those times, one sail was with Steve and it was literally epic (7m on 107 in about 20 knots and had a ball).
The D'Entrecasteaux Channel also offers what looks like excellent spots, especially out off Gordon and Verona Sands. However, our prevailing WNW winds would be mostly off-shore at these and a lot of other places in the Channel.
As most people have said above, the most popular spots for sailing are on the Eastern Shore. All within a short distance you have bump-n-jump, flat-water and waves. There will always be others out when sailing these spots, unlike any of the spots down the Channel/Huon area, where you're likely to be the only one.
For me, I do the shorter drive to work each day and put up with the extra driving for sailing, but it would be nice to live right next to where most of the sailing is happening. Having said that, it's only 40 minutes to Doran's.
If you move to the Channel/Huon area you may find the grass to be greener on the Eastern Shore!!