The ammount of defection really depends on the open valve spring pressure.
More aggressive profiles require stronger spring pressures.
It's safe to assume that the less metal there is to stabilize the cam's going to flex easier.
Some flex is actually normal & depended upon (keeps parts from being brittle & breaking).
Too much flex & bad things happen.
I'd just build it and follow the manufacturer's specs.
It should be fine as long as you don't "ride the limit".
(go with the biggest profile cam you can stuff in it)
BTW I'm just a novice.