So far so good...

I have double digit rigs with different card setups, I have not tried Phoenix Miner on any of those yet.  However I did try it on my test single GPU test machine.  It is right now a solo GTX 1070.  It was getting 29 to 30 mhs consistently at 62C on Claymore 11.2, rarely get stale shares with this card.

I started testing Phoenix Miner an hour ago.  I am getting 30 to 31 mhs.  It seems stable, same 62C.  However it seems my Effective speed is lower with Phoenix Miner at ethmine.   Then I noticed that in the short DEVFEE transition, it found 2 shares for the Devs while in the first 30 minutes it found just 6 for me.  So my effective rate(the actual rate measured by how many shares I find) at the pool is still 22.71 mh/s, but after a couple hours I will see if it catches up.  With Claymore my effective hash rate is pretty close and sometimes more than reported hash rate at the actual pool.

Overall it seems stable and if this small 0.5 mhs difference in speed on this one card is legit AND the dev fee is really legit then this looks like a possible better alternative to Claymore.