You can substitute 3 to 3 ½ teaspoons of pumpkin pie spice for the individual spices, "in a pinch" or if you prefer. Subbing pumpkin pie spice for part of the spices (allspice, cloves, ginger, and nutmeg) in addition to cinnamon is also an option.
You can use a sweeter apple, like Golden Delicious or Pink Lady, or perhaps even use more apples than pears, or all apples. Adjust honey (or other sweetener) as needed when altering the ratio of fruit and to personal preferences. Slow cooking will deepen the flavors, but it won’t necessarily make your pumpkin butter sweeter so being happy with the sweetness before adding your mixture to the slow cooker is important.
Slow cookers can vary in temperatures and required cooking time. You might need to slow cook your pumpkin butter more or less. Pay attention to that final cooking time the first time you make this recipe and note it on the recipe so you won't have to keep checking your pumpkin butter when you make it in the future.