Increasing brace height will increase the bow weight by maybe 1-2# but remember that it will also affect arrow tune by weakening their spine. Changing your tiller probably won't make any noticeable difference.
If your trying to gain distance for your barebow field shooting, here's what I'd do, in order of increasing expense outlay. First, make sure your nock point is at its optimal setting. If it's too high, it will reduce your point-on distance. Learn to facewalk and stringwalk. Practice a lot. Shoot the lightest arrows possible (properly spined of course). Get more efficient and/or heavier limbs.
Changes in trajectory was not the intent, just trying increase my tune was my goal.
Toward the end of our club's field league, I decided to raise my brace height because according to my owner's manual it is the recommended BH. It did do what it said it would do, it quieted the bow down a bit. I did not, however, notice an increase in DW.
The thing I noticed the most is my gaps are WAAAY off, so bad that I stopped shooting for score and started shooting to find out what was wrong and relocate my gaps. I am not the best archer by any stretch, but it was bad, and frustrating! My arrows were landing about half as high as they did before the change.
There is no simple or general answer. There are too many variables. It is not physics or science but craft, art and psychology, maybe magic is involved. Once you get reasonably close you have to work it out for yourself over time. Sometimes the difference between right and wrong is tiny.
It takes months and years to work it all out. That is one of the charms of archery; it can engage your interest for a lifetime and you can keep learning for decades. Trust hand, eye and feel. When it comes together it feels wonderful. - lbg
When I was shooting FITA target I was worried about how any little impact would affect my sight points at the longer distances. It was kind of like what happens when you have your first baby. You are very careful to make sure everything is sterile. The second baby comes along and when you find him eater dirt you ask if he wants seconds. An out of tune arrow will produce drag. How much that drag impacts cast is the question. I think Cody did some studies that might shed light on the subject over on Tradlab.
IMO, if you started off with a good tune then those changes shouldn’t affect things much with fletched arrows. I’d expect bareshafts to react more strongly, but not sure it’d be too drastic, especially at shorter yardages.
I made it to the range this evening, and the verdict is, I must have been very tired because I use the normal gaps and my score was 38 points higher than the last time I shot for score.
I walked by the unmarked targets today and it looks it will interesting because some of the targets are in the middle of the brush. One target it at the top of our tall shooting tower and we shoot from the ground up over the stairs. One target is shooting down from a shooting stand down to the ground. The marked range is the same as our FITA league targets, and the unmarked target range distances are determined by the target face. So it will be interesting to see how I do with the unmarked distances.