If you already have a 1070, it's definitely worth mining with it.
If you do not, it is NOT competative on the basis of income generated vs. cost of card - even on ZEC which is currently it's BEST income generation, the AMD RX 470 and 480 beat it fairly easily on a cost/hash basis.
If you plan to use the card for something OTHER THAN mining on the long term, it can me worth mining with it to help pay for it.
It is NOT in fact a more recent card than the RX 480 - the 1070 introduction PREdates the RX480 introduction (much less the 470) by 2-3 months.
this is wrong how the amd 470 and 480 are beating the 1070 on zcash?
just look at the hashrate, the 1070 can do 380 sol at 100 watt against 200 sol at 90 watt for a 470
even if the 470 cost half of one 1070 it's still not better to go with amd, especially if you are going to have many rig where density matter a lot
also by the look how people consider cost/hash they always forget that 4 rig are always far better than 8 rig(if they both perform similar, 380 sol x 6 x 4 vs 200 sol x 6 x 8 ), because you save on computer components that do not mine so you save on cost/hash in the end
not to mention that you save on the consumption as well, 700 watt x 4 rig against 600 watt per 8 rig...no question nvidia is far better, amd is trash at the moment on zec
470 at CURRENT pricing is closer to 40% of the cost of the 1070 not half AND HAS BEEN DROPPING due to competition from the 1060, *AND* is quite a bit more efficient on algorythms OTHER THAN the one used by ZCash - making yourself reliant on ONE specific coin to achieve ROI is a fools game when the coin has shown NO staying power on price and as many core ISSUES as ZCash has had.
Insisting on the 470 mining ZCash *right now* when it's more profitable on ETH and a pair of 470s ON ETH are pulling in about 20% MORE than a single 1070 on ZEC blows your numbers completely away.
Most miners are NOT going to lock themselves into a less profitable coin for any significant length of time, and that doesn't even factor coin-switching multipools into account.
System cost ends up being at best the same per hash, in MY calculations, on 4 card rigs - you can't get away with or COUNT on that "100 watt for 280 sol/s" figure on ZCash for the 1070 as
MOST 1070 don't achieve that, more like 140 watts based on MY stable of various 1070 cards, so you DO end up having to put a beefier PS on a 1070 rig - especially if you don't COUNT on ZCash being profitable for the long run (which is the SMART play).
For the 1070 to become competative on XMR, it would have to achieve closer to 1400 h/s not 900 h/s - 470s RIGHT NOW are widely posted to be achieving more than 700 h/s on that coin.
I can see a faint possibility of that - the 750ti manages 250 - but if XMR is as memory-hard as ETH is that's gonna be a pipe dream.