Actually the 10 and 30 is kinda normal because of the arc in your arrow flight. So long as you know that you are high at 20 you can compensate for it while shooting.
I use a sliding sight and I set my sight at 30 yards and that's how I hunt. Your muzzy broad heads will work just fine for you, they are not my favorite but they have been around for so long for a reason.
If you are going to shoot for past 30 yards you need to make sure that you are very proficient and that you are only shooting at animals that don't know your their. I have learned this the hard way through experience.
* (Swinging club) Whack! whack! whack! *
Nope, the old nag's still dead .