As a solo crafter, having tried the GR courier quests and having gained access there and crafted there, Glow, Mariposa and Toxic Caves, i can tell you that from a pure risk standpoint i consider GR to be the worst option available. All you have to do is lose a courier case and it's all over. To get that crafter back on track you have to find some way to get a replacement case. People will say "so what, just level a new guy to 5 and get a case for him" but yeah that's not the kind of crap i'll go through to craft. That should carry some weight too because i'm a mining/gathering/crafting machine who is willing to put in serious time in this game. I have 10 bases now but i'm not going to stop my whole operation to get a replacement case when i know i'm only going to lose another one soon enough. Forget that.
I just now logged into my lockpicker and found 2 encounters hoping to find BP. I died on 2nd encounter due to server lag spike. So imagine my crafter delivering cases back-n-forth to SF; he will die at some point and lose a case. From there his GR rep starts dropping back down.
And GR itself? Yeah Ed said it right: war zone sometimes. I lost a case there too. It was a group of about 15 Polish guys i think, nobody speaking English (Wichura was there!) and one of them rocketed me as i was exiting. I admimt i should not have even tried with that many guys around, but the point is...it's simply too easy for that GR plan to fail. I'd rather craft at Glow and get radiated. If i get PK'd there, at least it's a PK whose working for his loot rather than camping a place that's supposed to be safer. Mariposa dogs are easy compared to GR campers. Yes PKs at Mariposa too but i can fight them there and i don't lose rep with anyone.
GR is this crafter's least favorite crafting option: time investment vs. certainty of eventual failure there + irritation to recover.