After several rounds of testing, I have come to a couple of conclusions about the 70D + nifty fifty (EF 50mm f/1.8) combination.
1. At close range, it works splendidly, no matter the focus point or method.
2. This thing needed some serious MFA; I've settled on -10 for now using the dot-tune method.
3. At distance (in my case approximately 17 feet), this lens -beit this copy or this lens in general- is horribly inconsistent when using phase detect (through-the-viewfinder) focus.
4. Live view - the 70D's much improved, fast as lightning, dual-pixel live view - is far more consistent than phase detect, with this lens.
So, as one example (of three I did, but this is the most easily compared), I shot a test chart. There is a lot of light on the chart (two shop lights w/ 100W CFLs), so lighting isn't a problem.
The test setup:
Results w/ 50mm f/1.8
On the plus side, the center focus point doesn't seem to be any better or worse than the above- or below- center points. Live view is much better than all three.
By contrast, here is the EF-S 18-55mm IS STM using the center-point.
This is obviously inconclusive and I need a better lens, which I can't afford. However, here's some testing for you to mull over, for what it may be worth.