In your opinion, would I notice any changes by going to a better scale and trickling?
What would you say about your vertical or waterline now?
The x-ring being half MOA, are your groups sub half MOA?
As a side note... Once in a while the midrange match at my club gets very popular. Normally done at 3X600 with three relays shooting three times, a match ends in about 4 hours. But, on some occasions there were only 5 targets available and more than 3 relays worth of participants. The MD decided to split the match format to be 2x 15 shots at 600, and 2x 15 shots at 300 to allow for more targets and shooters.
There was lots of grumbling from some of the regulars. Many felt that 300 yards was beneath them or too easy...
What came out of that match was more dropped points at 300 than at 600 for many of the Masters and High Masters who were grumbling earlier, but some had it under control just fine. Those tended to have some XTC experience and knew that the 300 yard line could still blow you out by a ring if you were not watching your wind. The sling shooters fared better cause many were XTC shooters, but it really bit the F-Class shooters who didn't take care.
I got the sentiment that many of them didn't care for shooting the 300 yard line at the start since they came with 600 in mind, but by the end of that day many didn't think it was easy or beneath them any more cause the wind handed them their hat.
So fatelvis, for anyone to guess at if a A&D FX120 will make any difference in your scores, the answer depends on how tight you are shooting now and if your issues are the control of powder charge or due to other stronger effects like being at the wrong tune in the first place, brass, bullets, powders, etc.
If your verticals are <half MOA and your ES is below 30 for 20 shots, then probably not noticeable till you go to past 600. If your ES is below 30 and your vertical is above half MOA, then something else is probably wrong.