Really it comes down to you either buy some S7s now, or wait a moth or two till the next price drop/new model. If your going to buy now, do it. If not, wait.
Or you just pass on mining all together.
"Now pick up your skirt, grab your balls, and lets make some money" "Your gonna pass? The only people I see making money passing are NFL quaterbacks and I don't see a number on your back" -From the movie Boiler Room, one of my favorite.
I view passing as a valid investment strategy as far is someone want's to hold BTC vs say mining. I don't view valid the people who always say " wait a moth or two till the next price drop/new model", in my eyes a lot of these are just talk. They always say they are waiting on next gen and never pull the trigger on a sell.
The two current ones are S7 and Avalon 6. OP should do some ROI math before any investment. And never invest more then he is able to lose.