This week I head for the mountains for 2up touring with a couple vintage buddies (78 BMW, 76 550). I'll be in a better position to answer these questions Monday.
After about 100 miles testing, here's my findings.
The added beam helps reduce saddle bag vibration. Its still not perfectly solid due to the nature of the mounts.
There is just no satisfactory place to tie down the front bottom parts securely without it detracting from aesthetics or consuming passenger leg space.
The saddle bags, alum supports, top case are pretty light. The top rack is by far the heaviest item.
All the cases are super light almost to the point of being too fragile.
I got the small top case on purpose because I didn't want it to be a disturbance.
I haven't noticed additional vibration, whistling or strange handling characteristics yet.
It all feels solid. To judge the saddlebag vibration, I have to reach back and touch the cases while cruising.
Usually the biggest change is just riding with another person. My stopping distance get much longer of course.
That one disk brake heats up easy with all the extra energy to consume.
I did notice updating the swing arm bearing and steering needle bearing helps the bike dance the extra weight better.
I'll have more to report as this is my substitute Goldwing now.