I also want something I can't do aggressive bottom turns on, without sliding out
Do you mean you do NOT want something that you cannot do aggressive bottom turns with?
Just from what you write, I think the global might be a better option. Now I LOVE the skaters big time, and I ride the 4'8'' and 5'4'' a lot.. I have ridden the bigger one quite a bit too...but find the smaller ones easier for air., and though you CAN certainly go with quite a bit of power, the power you generate with a kite is a lot.
I have never ridden the skaters with straps, but can imagine the 5'4'' and 4'8'' to work with them. I do know a guy that loves his with straps. I would probably not use the bigger skater with straps.
Now for the global, if you go for the medium size I am sure that will rock strapless too. Check out some of the videos from naish you can clearly see they are using the global strapless when the wave size increases. When the wind increases the global is a lot easier to handle both in terms of chop and power.
The Naish boards comes with solid fins. I tried some plastic fin to loosen up the ride, and snapped them on the first top turn.
I'd say if this is for your aggressive / powered riding go global. If you do go skater, then go with the 5'4'' for sure.
As far as I can see the skater + global lineup has been the best Naish has had for a long time. yeah yeah I know I like a lot of the Naish boards, but I have ridden these a lot...barely take out my other boards anymore.
Also something to consider: The skater does not come with straps. Global comes with straps, bag and quad fins and 5 boxes. Skater is thruster. except the 4'8'' which is twin.