The OP does not mention his position hence we have no idea of the rules we are bound by.
Aerocat has summed it up pretty well. If Aus based read the AIP, it tells you how much clearance it gives you if the gradient is above 3.3. It might give you shivers if you cannot guarantee your gradient.
The long and short is, you must comply with the climb gradient! If you have escape procedures established that's great, but if the failure occurs after the escape turn point what will you do?
Most larger aircraft have the capability of up to 4% on one. Assuming it's a twin. As Aerocat has said through if they struggle to make it on all 4 on a flex takeoff, they have real problems..
I suggest any depiction of a gradient above 3.3 is likely to be of risk to the aircraft and it needs to maintain the minimum FPM. If it doesn't and for example following engine failure maintains level accelerate, legally where are they? They wouldn't know until above LSALT?
SID's are set for traffic movement and terrain/ATC LL clearance - when you abide by the SID.
Cheers All!