Okay, I've been mining to the VTC pool at multipool.sonofatech.com for 45 hours with very few rejected shares (99.8% acceptance) and my earnings are finally approaching the predicted amount. It's still underestimated, but now the difference is between 0.26 reported vs. 0.34 predicted, rather than 0.003 reported vs. 0.17 predicted... I suspect the long time to find a block at SOAT - around 12 to 16 hours - is partially to blame for the under-reported earnings, and if so, then the estimation should improve the longer I mine there. As a result, I am going to give it another day at least, even though I was planning on switching the mighty GTX 1050 Ti over to mining ZEN this morning.

The situation at give-me-coins.com is even worse: the time between blocks is estimated at 105 hours!?! So while I no longer think there are shenanigans going on at GMC, I also don't want to waste time mining there; 12-16 hours between blocks is already trying my patience as it is.