I agree with Rockmagnet...
I have an 8'10 Speeed and find it can seem tippier than it actually is.

(I was 90kg, now I'm 85 - and I guess practice and a few lost kgs have both helped me get used to it.)
That initial "uh-oh" then recovery is probably the secondary stability thing that people talk about - it feels like you're about to get tipped off, but if you wait another nano-second, it's okay again. So, don't listen to your brain, is the important thing.

But I also have a bigger board for when conditions would make life hard work on the Speeed. So that's the other important thing - when in doubt, buy another board for the quiver.
I'm 55. I reckon I'll want more volume in a few years. I think age is a BIG factor even for fit, skilled surfers and the years should be factored in to board choice right along with weight, experience and your usual conditions on the water.