I dont understand why would you have issues with parts fitted from GSA on standard GS ?
Regarding touring, other than the range, what are the advantages of GSA ?
I have ridden to CT and back on my gf's F800ST, two up, with top box and panniers and bike never missed a beat.
We did Kalahari (Uppington to Paternoster) just after Xmas, in 45C heat...other then me almost collapsing from heat, everything was fine.
I think he is talking about aftermarket components, not OEM......
Advantages in my humble opinion:
Larger screen & winglets gives better wind protection
slightly higher (which I like)
more plug & play luggage options, no extra brackets needed(hard, aftermarket).
The GSA looks much better than GS
Better suspension
Standard aux lights
Standard crashbars upper and lower
.....and the extra range.....
If you had to "improve" all of these on a GS, it would end up costing more than GSA
Its a miss match of OEM and aftermarket and boer-maak-n-plan add ons. Loads of stuff bought second hand on the forum.
Example, the GS support for topbox is plastic. Replace Vario with Trax and suddenly its more forward and there isnt enough space for the pillion. new holes in support plate scores you 3cm maybe, not enough. So buy bracket on forum (not GSA OEM, GSA ones are expensive and rare second hand) and now the Trax sits perfect....first Lesotho trip heavily loaded and the bracket beds, I look like a loaded Hilux out of the townships!
Just an example, it becomes a learning curve, even with the best of intentions.
The other thing I had issues with were the GSA windscreen, coming loose, rattling or loosing screws. And I have used rather a lot of Loctite on my bike to date. At least I also learned a lot in the process.
Just saying, I am not the most technically minded person so I may be a stupid example, but you can have your own unique issues

GS looks better to me though, especially if silver alluminum fairings are made black. GSA looks like a stokkie-lekker