soft board bouyancy compared to 7,0 mal

Hey,
I've got a 7,0 minimal (sideways bullet). It's designed to be a bit thinner to allow for turns than anormal mal. I want to get a foam or soft board so I can surf in between flags. my 7,0 is 21'' x 2 13/16'' (46.5 L). I'm just wondering if a 6,6 foam board will be as stable as this 7,0 or more stable due to its extra volume, etc.?
I just don't want to buy something that is too small for me in terms of stability
Best,
Lachlan
I've got a 7,0 minimal (sideways bullet). It's designed to be a bit thinner to allow for turns than anormal mal. I want to get a foam or soft board so I can surf in between flags. my 7,0 is 21'' x 2 13/16'' (46.5 L). I'm just wondering if a 6,6 foam board will be as stable as this 7,0 or more stable due to its extra volume, etc.?
I just don't want to buy something that is too small for me in terms of stability
Best,
Lachlan