From my experiences, Velcro has been extremely durable in terms of securing electrical equipment; even with the challenges that had quite a bit of contact. I don’t recall us having any issues with Velcro failure/flex during Aerial Assist, which involved some heavy defense. That being said, if you’re still concerned like I often am; I’d recommend using zip ties as they’re strong and efficient in terms of time it takes to install and remove for maintenance.
Through reading the concern about bumpy defenses such as the rough terrain; I’d say it’s vital to have a sturdy and ergonomic belly pan to protect much of your electrical if you plan to house devices towards the bottom of the bot. Placing some sort of foam beneath your electrical board could even help in reducing the shock exerted by the obstacles.
P.s. Here is a link to the Velcro our team usually uses; it’s fairly strong which I believe aids in the lack of flex/oscillation.