David,
To me the heavy cap on your Adams gives the horn a bit more gravitas. I would say it put the sound more towards the classic British direction. Also sounds a bit more resonant. With the stock cap it sounds a little more brittle and perhaps bright. I can hear the difference, particularly in the lower-mid range. Definitely prefer the sound of the heavy cap, though both sound wonderful (as do you!).
Doug
Adams E3 0.60 Sterling bell - Prototype top sprung valves
Concord Band
Winchendon Winds
Townsend Military Band