For the conditions you propose I would recommend you choose and buy a Goya Bolt they have 95, 105, 115, 125 and 135 litre boards to choose from. It is a free race so it is fast end of free ride but handles chop well, it was developed in Hawaii but will be fine for the flat water you propose. I have a 115 Goya Bolt and it is "flat out fast" for me. Top quality premium carbon monocoque construction with excellent finish. Goya says this:
"
.....The Bolt's rocker has an almost continuous flat section from behind the mast to the tail, with the lightest release off the tail for unlimited speed and acceleration. A concave deck drives the power of the rig lower and forward on the water. Tail cutouts bring flotation to lower speeds and reduce the wetted area on straight speeding lines. The Bolt gets up and planing on the lightest breeze, and paces through gusts, allowing you to forcefully ride on the fin with direct control. The outline curves and rail shapes project you out of jibes like no other board...."
Review the review here:
doggiebagwindsurfers.wordpress.com/ and here:
www.windsurf.co.uk/test/goya-bolt-115l-2016-test-review/Specs below:
Bolt 95
Volume: 95ltrs.
Length: 236.7 cm
Width: 61.9 cm
Weight: 6.2kg
Fin: MFC KP RC 36 TT
Sail Range: 5.0-7.5
Bolt 105
Volume: 105ltrs.
Length: 235.3 cm
Width: 64.1 cm
Weight: 6.3kg
Fin: MFC KP RC 38 TT
Sail Range: 5.5-8.0
Bolt 115
Volume: 115ltrs.
Length: 241.5 cm
Width: 71.8 cm
Weight: 6.8kg
Fin: MFC KP RC 42 TT
Sail Range: 6.0-8.5
Bolt 125
Volume: 125ltrs.
Length: 240.1 cm
Width: 76 cm
Fin: MFC KP RC 44 TT
Sail Range: 6.0-9.0
Bolt 135
Volume: 135ltrs.
Length: 242.8 cm
Width: 80.1 cm
Fin: MFC KP RC 46 TT
Sail Range: 7.0-10.0
Video here: Test Review: Goya Bolt 105 and Mark 6.2 Sail
There are loads of video on you tube and vimeo for these boards.
Goya is also releasing a Slalom board for 2017. It is going to be used in the PWA with Rider Gabriel Browne for 2017 with Maui Sails. Search the web for more information on the Goya Proton and videos.
Good luck with your search for the right board for you, enjoy the "retail therapy" and best wishes for your choice.