Hi Tom and Filippi,
For Tom: What "Roger's Adj. OH system" parts are you using..... just the Harken blocks on the clew of the sail, or the whole set up with Harken blocks on the boom as well.
I have some photos of the 623 blocks setup for the clew that I can send off to Filippi.
As far as the power of the 6.6 Hucker, again I submit that it makes alot of difference what mast you use and what your goal is.
Use a SW Backbone RDM, and you get max power. Use a Powerex 460 RDM and you get almost as much power but the upper leech twists off a little more.
Use the recommended 460 SW Joystick and you get slightly less overall power, with very limited twist.
How much you downhaul and outhaul can really change the overall available power.
Do I think the 6.6 Hucker makes as much power as a 7.5 Retro?...... close, but as Tom (Viking Sail) suggests, if you take the 6.6 Hucker out when it's really 7.5 m2 conditions (i.e. < 14 knots probably) you can probably get going, but you could probably get going a little easier on the 7.5 Retro, simply due to the larger size/area of the 7.5m2.
If you have alot of 7.5 conditions, then I'd stay with the 7.5 Retro and trade in the 6.5 Retro on the 6.6 Hucker. If you are almost powered up on the 6.5 Retro a lot of the time then sell the 7.5 and get the 6.6 Hucker.
Yes, the Hucker will feel nicely balanced and smooth (even slippery with enough downhaul) in a slightly wider range of conditions than the 6.5 Retro.
Right at first (like the first few minutes) the Hucker may feel a little more powerful in the top of the sail (pitchy feeling) but you will adjust to that almost immediately and then the sail feels powerful, balanced, and slippery.
Hope this helps,