I shoot thunderhead 100s . They seem to shoot almost identical to my field points. This is with an Easton ST Axis 400  arrow 9gpi , 27 inch shaft.

Every combo is going to be different.  The only way you could 100% go on somone elses set up would be if you had the same bow , tuned in the same shop with the identical draw weight , same model and length arrow , same arrow heads , same release , stance , grip , sight ect ect.

Personally I sight in with field points. Then I designate one broad head tipped arrow for a target arrow and mark it. Then I adjust my sites for the broad head and shoot for a bit making sure its dead on. THen I aim at a spot and shoot my field points. Somtimes like with my current cmbo u get lucky. Other times You do not but leave your sight alone ( its dead on with your broad heads so why change it) aim  for where u want to shoot and shoot every time at that spot. You already know its dead on with your broadheads so who cares if your field points are going an inch high and 2 inch left or somthing..... you are practicing for repeatability and consistancy not killing a black dot.  

After not shooting for many months. I shoot a group of 3 field points , a 2nd group of 3 field points at a different dot. Then I put the bow down and relax for a min. Have a sip of soda , pet the dog.. what ever to clear my head. I then picking up my bow , knock my practice broad head , raise my bow to my point of aim and fire.  You will be suprised how accurate , smooth and natural you will make that single shot and if you set your sights right the arrow that counts the most will be dead center of your kill zone , dot , target what not.