The incentive is there for Everton. If we can win, we go level with West Ham and could finish in 8th or so if we have a strong finish to the season (which would be acceptable as a 'learning curve' season).
United are shit-hot though right now and are probably the best they've been since SAF left. But we generally do well against them at Goodison. Hopefully the fact that a win can move us into the top half and that we will not be thinking about relegation battles will both be conducive to a more relaxed and confident performance.
Usually Everton have a couple of great performance throughout the course of season. This season we haven't had any. This may be the one we are due.
On the balance of everything, I think it will be a score draw.