I don't want to sound negative because a lot of folks are hot to convert to a dual disc setup, but I've been very satisfied with the single disc on my '84. And from what I've heard and read, there is little or no appreciable increase in stopping power by adding the second disc. I'd be curious to see some properly conducted stopping distance stats comparing an '82-'84 LS with a same year, single-disc Standard model. Wonder if BMW has this data stored away somewhere?
Single or double disc, the R65s will never come close to matching the stopping power of modern bikes, and considering the bike's size, weight and performance, the single disc has been quite adequate. Better brakes would be a good thing, of course, always is, but I don't think adding the 2nd disc is how to get them. Just my opinion, but it also takes into consideration several instances when I've had to shut down quickly, and I've never lost control or locked the wheel.