Yes,my GTX960 was lower power than a R9 380 but now I wish I had not bothered.
Plus,seriously, I have a mini-ITX system so if you really can't afford to run a RX480(which is really not that much higher power consumption than a GTX1060),why don't you buy a GTX750TI??
I have run cards like the 8800GTS 512MB and HD5850 1GB(I overclocked mine by nearly 30%) running fine off 400W/450W Shuttle PSUs.
Thermals (AMD cards run hotter)
Not always - since it is more down to power dissipated over die area. A Fury for example is cooler running than say a R9 290 partly as it is a 600MM2 die against a 438MM2 one,and load power was no different.
Plus my mate had a 9800GT in a ammo box SFF system running at 90C under load for like two years.
It still works in 2016 in another rig.
I had plenty of Nvidia and AMD/ATI cards run hot - people forget how many cards had single slot coolers like the 7900GS and X1900GT. Run those in a SFF system,then you will see what hot is.
Vendor quality (no EVGA etc)
Gigabyte make AMD cards too - in 12 years of owning graphics card,I had two go. Both were Nvidia. One inside warranty,the other outside and probably it was the bumps issue which did it for the first one.
In terms of all my mates in the last 10 years,I think one destroyed their 9600GSO by volt modding it,one mate had issues with an MSI HD6870 out of warranty(but another mate tried it and it is fine so must be the magnetic ball bearing he found stuck in it) and I think the only card recently I saw an issue with is a MSI HD7850 1GB two years ago which was well within its warranty,plus the one last year I had.
Furthermore, I've read various reports of the most popular 480, the Sapphire Nitro having coil whine, high temperatures and loud fans.
Mate has one,and has not reported any problems with his.
He did have the XFX 7800XT of fail - that was a hot running card,but it still works and was apparently a card made of bits and pieces which one or two retailers sold here cheap(only a few 100 made and no wonder). Told him to avoid it.
I do hope the RX 480 does greatly improve, as this might actually give nvidia some competition and reduce prices as a result.
Apparently from what Gibbo is saying they sold more RX480 cards in the GTX1060 launch week than GTX1060 cards(and more GTX1070 and GTX1080 cards too).
If anything AMD barely keeping up with demand is probably what is going to cost them,since its hard to actually buy an AIB RX480 cards now unless you want to play the waiting game.
Edit!!
Remember,another person I know has the Nitro card and he upgraded from his GTX580. He also seemed reasonably happy with his.
Can't comment on any of the other ones sadly.