I can't comment on those 7,7 and 7,10 size ,just out of my weight range at 98 kgs ...
but my 9,1 acid is my go too board ,but the 8,7 flow is my little board .
flow tail might give you the extra lift ,and yes they are more stabile ,i love my 8,7 in small waves
it has extra speed ,and seems looser and loves doing tail slide

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if its 2-4 foot and clean the flow rips ..it really is a fantastic little board ,
the acid is better in more powerful waves .
you could also go a small acid ,jump to the next 2 size down ,from your 9,1
as a thought .eg.8,7 acid .? has 108 litres i think ..cantsupenough has all 3 sizes ,maybe worth talking to him .
but its good to get exploring other board .the flow has more speed and might be what your seeking . I Like both .

they both have good things about them ,as you know the acid has a more pulled in nose and tail and the smaller sizes will take some skill in balancing .so maybe the flow will be the good add to the quiver .