I run an 11-36 SRAM cassette with my 105 GS RD with zero issues. I put a Praxis Alba crankset (48/32) on my bike and I've got a hair under 1500 miles on it with zero issues. Granted I don't do a lot of riding in the muck but a whole lot of dust/dirt.
I've been happy with 26 gear inches on the low end with a range of about 491%
Granted an 11-34 paired to a 46/30 would be a touch lower 25.9 vs. 26.1 and some tighter spacing towards the bottom of the cassette, there's no frankenstein-ing to achieve these results with 105 and zero additional accessories.
Not to mention the tech is available right now and from my experience 105 is durable, reliable and most importantly readily available.