Of course the relative differences are obvious, but I'm not sure direct comparisons are relevant with powder application. I say this because, for example, compare .222 case and .45-70 case, then .224 bullet and .458 bullet. IMR 4198 is a good performer in both dispite their seeming dissimilarities.
I was wrong about an Accurate Arms recommendation for 1680 in .45-70. I went back and looked at their web site again and the large, straight walled cartridge for which they give data is the Marlin .444. Still, it is a straight wall case.
In looking over the AA data again, I notice they give an application for using 1680 in .32-20 revolver loads which is something I might be interested in also. I think the old Winchester recommendations for .32-20 loadings were in W-630, which of course was a different powder.
Thank you for your input. I probably won't do anything with this powder as I have so much other powder that is more appropriate for the calibers that I load. I would like to have a .22 Hornet or a .25-20 WCF someday, so I may just save it for that time. 680 can also be used in .30 Carbine, but I'm done with that caliber.