Tune your bow and use the right spined arrow and there should be very little change. That being said there will always be some difference.. Using a Hooter Shooter and a dozen .001 correctly spined arrows and field points will normally yield 9 arrows on average that will hit in a 2" group at 50 yards. Put BH's on those arrows that are fliers and you have a 6"-12" difference. Someone that says that they have all their arrows BH or field points hitting identicle is not all together the truth. Especially at longer distances. But you can get them in the accptable range.
Now for Montecs. Yes they are a great BH, strong and fly like FP's. The problem is that 90% of the archers that use them do not get them sharp enough to create good blood trails. They kill the animal but there is very little blood even on good shots. I saw a bull last year that was shot at 2 yards right through the heart with a G5. No blood trail. Granted he only went 40 yards, what little blood there was was quickly soaked up by the fur. When we examined the heart it barely left a whole it actually pushed the arteries out of the way instead of slicing through them. Almost an identicle shot placement on a cow that day with a shuttle t produced a massive amount of blood and a huge hole through the heart slicing everything in its path.
As for straw bails. Unless they are compressed at 2000 psi they are no good for stopping arrows and definately not for BH's.