I can give you my 2 cents on Hobie 18s regarding pitchpoling. First, the Hobie 18 is the least likely catamaran out there to pitchpole. The bow design on the boat was to specifically prevent that (in my view),
Next, mast rake will have very little effect on whether you pitchpole the boat. The largest impact on the boat having a tendency toward a pitchpole will be determined by crew weight location or water in the hulls. The first ingredient needed is big wind. There will need to be significant wind to set up a situation where one might become concerned about pitchpoling. You will not be in any danger unless you are driving off on a reach in big wind. If you get lifted up on a big wave and are surfing down that wave and the crew does not move weight towards the back of the boat then you will have risk of a PP. In this same situation, if you have a lot of water in the hulls, that water will rush forward when angled down and can cause the bows to dig under water. What I have seen take a boat over is when you are turning, say the windward mark and going on a reach with a crew member on the wire (or both) and they have no way to keep themselves in the back of the boat. They will swing in the trap to the front of the boat and the result of that weight going forward will add to wind pressure on the main and can result in a PP. In these examples it will not matter about your mast rake.
By the way the general rule is you rake the mast back for ability to point up wind better, however that will depower you down wind. It is a trade off, so which area do you want your strength, up wind or down?
When I sail up wind I try to have the leeward hull about 1 inch from going under. As wind builds and it starts to go under water, I start moving weight back also trying to maintain that 1 inch of the front of the hull above the water.
Also as a safety note, even going dead downwind, if the wind gets high enough (30+) all of that pressure will be pushing on the main, which will push down the front of the boat. There is a point where the hulls will go under and any boat will PP, including monohulls. This is why boats will shorten sail in heavy air. In these extreme conditions, if there was some lift in the front of the boat from a spinnaker, then the boat will be more balanced from the pressure that is pushing on just the main, which will provide lift to the front and one can survive longer, until well... you don't
Bottom line the Hobie 18 is the safest boat from a Pitchpoling perspective. I have stuffed the hulls into the water up to the front cross bar without going over. The boat just stopped, backed up out of the water and took off again.
Again, how far you rake your mast is not about pitchpoling.
Cheers, and good luck.