I've seen plenty of good lefties in the area dominate house shots (and some tournament shots) throwing high rg stuff. I don't buy that argument one bit. I've witnessed one of them shoot 800 with a hyroad pearl from start to finish on fresh conditions. The ball did anything but lope.
As for the hyroad nano, it most certainly does not lope. The combination of that core and coverstock makes it a beast on the lanes. I throw 14lbs, and if you look at the numbers, it should be even more prone to lope than 15 or 16. Not even close. I have not thrown the Phase II myself - other than at a demo day. However, I've seen plenty of others throw it. They aren't that far off.
Coverstock does have more of an effect than the core. I think some people get too caught up in the numbers and convince themselves it won't work. Also, those core numbers change when a ball is drilled.