Alan,
Detail levels at different magnications is something I've checked out a few times over the years, swaping different binoculars in and out of the test group, and the result can be really quite variable.
I use a line chart to get a fairly pricise estimate of the limit of detail I can see. The first occasion I did it standing, hand held, I got pretty much the same value for 7, 8, 9 and 10x, which wasn't too much of a surprise given the consensus on the forum at the time. The odd one out was the 12x which was a very useful 30% better than the others. The key point was that, while heavier than I would like, it was well balanced in the hand and was less affected by shake.
Since that time, my 7x, 8x and 10x have been replaced, and now I'm close to getting the same proportional increase in detail as would go with the magnification. In fact it's the 8x that is now slightly out of line and is the leading candidate to get replaced again. However, I do have my eye on another 12x50 I've tried which was even steadier than my old one.
I fully accept that other users will have quite a different experience of how much detail they can see at different magnification, but you might just get a better result using different binoculars?
David