I cannot answer your question about a larger Hucker.
I think a number of sailors (me included) have encouraged Bruce P. (Sailworks Owner/Designer) to consider a larger Hucker, but I haven't heard anything about him
actually working on a larger design.
As far as the Retro 7.5 vs Severne Glide 7.5, I also encouraged Bruce to take a Glide for a sail.
I actually sailed the Glide 7.5 m2 quite a bit last year as when I put it on the super light 460 Redline 100% carbon mast and used a very light but very stiff older WS Hawaii all carbon boom I had a 7.5 m2 rig that weighed about the same as most 6.-6.5 m2 rigs.
The very expensive (but very light weight) fabric up in the top of the Glide makes the sail feel super light.
It's got very good low wind power with it's 3 cams.
But, I'm not sure the market is there for 7.5 or 8.5 m2 sails that are super light, super powerful, but cost twice as much.
To me, who doesn't have to pay for my sails, the super expensive stuff is so nice, I always tend to use it. To those of you who have to pay your hard earned money for
the super light/super powerful but costly rigs with pricey masts and booms, I think the designers are going to have to make them alot lighter, or alot more powerful before they sell a whole lot of them.
Also, limited production keeps the price high.
I'm looking forward to getting back on the water after my surgery pretty soon, and my first testing will be the on the new '08 Retro.
Hope this helps,
P.S. If you really want a larger Hucker, and are willing to pay for the develpment, I think Bruce P. would be amenable to making you one as a custom sail.