Well acrylic paint when applied right, then washed lightly is actually hardly noticeable. I mean when you wear it. Comfort wise.
And I've seen plenty of videos spraypainting their Doc Martens, so I guess that wouldn't be too hard on them. I guess its all up to you.
actually that boot looks pretty cool! ^-^ And if it does wear away, it will give it even more style. Or when its all gone you can do something else!
I like using pen on blue jeans, because they ink fades after a few washes, so I can doodle on my pants all I want, then do it all over again! XD