All engine operating SIDs, ODP, and missed approaches assume a constant gradient; i.e, no level segment for acceleration.
Perhaps that is understood here, but I am not so sure.
In the United States, if the constant slope for the SID, ODP, or missed approach is greater than 200 feet per mile, then a 24% additive is factored in to compensate for more likely performance errors.
Having said that, the FAA is seriously considering doing away with the 24% additive for two reasons: 1. The smart, conservative guy who sold the concept has been retired for some time now. 2. The airline lobby doesn't like the additive because it can affect payload (read: revenue).