You obviously didn't read this:
http://www.legitreviews.com/mining-xmr-monero-amd-radeon-vega-frontier-edition-cards-2050-hs_201259
They have three FE's running together producing 6,165 H/s on the XMR-STAK-AMD.
The 15 setup steps don't seem overly complicated.
As for your "mines slightly better than a 1070" comment I don't consider 2,055 H/s for the FE slightly better than the 761 H/s for the GTX 1070 but vastly better.
It costs double the 1070 but gives 2.7x the performance using your numbers. (This assumes you only want to mine XMR/CryptoNight)
If you want to compare apples-to-oranges let's use Whattomine to figure out something real quick.
I'll use Vega 56 since they don't have FE.
Highest ROI for Vega 56 right this moment: NiceHash at $8.45/day if you want to mine a coin to keep then Electroneum is generating $6.59
Highest ROI for 1070 right at this moment: GoByte at $6.52 or if you want to mine something more mainstream ZClassic comes in at $5.59.
So that 2.7x advantage is actually only a 29% increase when put to use generating real money.
You can combine 3 in one machine (I've read long threads of people struggling to get 2 working together, but ok) vs. 8 or more for 1070s.
So using those numbers from above 3x $8.45 = $25.35/day for a machine with $2250 worth of GPUs for a breakeven of 89 days with current pricing.
For the 1070s let's go with 6 instead of 8 just for fun so at $450 per card that's $2700 worth of GPUs generating 6x $6.52 = $39/day so breakeven at 69 days.
So, yes, there is a single crypto algorithm that Vega is particularly good with, but that doesn't overcome the GTX 1070 when it comes to real world application and ROI.
If I'm wrong somewhere, please show me.