An ounce per 100 miles sounds pretty normal since BMW specs oil consumption at something like a quart every 600 miles(Nobody here uses that much).
If the plugs aren't oil fouled but are tan in color, I would say that you are in good shape. It sounds like your rings and valve stem oil seals are in good shape.
As far as the Seafoam, I wouldn't put in more than half a can or run it for more than 20 miles because it thins the oil out and some lubricity is lost.. I would also do it with fresh oil and filter in the engine. The oil can be the cheapest 30 or 40 weight you can find and the filter can be a $4 Carquest replacement for a AC Delco PF53. Put the cheap stuff in, run for about 20 miles and drain it out, replace with a good synthetic and a fresh oil filter.
The main reason I did the flush to my bike was to clean the crap out of the sprag clutch. These are fussy little gizmos that need to be kept crud free to operate properly. After 25 years and 110,000 miles it was giving me some grief and the flush took care of the problem. If you watch the oil change intervals, I would think you shouldn't have to do the flush more than once every 4-5 years at the most. After all, it was nearly 25 years before the first one was done on my bike.