When you see an S9 hashboard providing approximately 4TH each it can put the competition in a different perspective. Truly price what you have gotten from your S9 experience against the competition and you may find the 6TH, etc much more cost effective, IE Avalon. Personally, Avalon didn't sit well with me by not accepting BTC as a payment option. This is our business and a company in this field refusing BTC as payment starts to rub the "principle" side the wrong way. However, I have been beaten to hell much less rubbed the wrong way by Bitmain China so many times I can certainly stand to be RUBBED wrong in one way or another from some competition.
They accept bitcoin, my S7s and S9s have such a high failure rate that even with the higher cost per TH, they end up working out to about the same, and from what it seems, the A7 has been quite like the SP20 in stability (all of mine still work after all these years)
S5s were amazing! no failures, S4, just as bad as the S9.