I have been testing 300mAh LiHV with a 1S PH2.0 toothpick and BT2.0 whoop; both weigh 24g without battery and both have the same electronics and motors.

PH2.0

Several 1S 300mAh PH2.0 LiHV PILLOW batteries I bought a year ago can barely manage 15 seconds of flight time.  Brand will remain unnamed.

When I use 1S 300mAh PH2.0 LiHV FOLDED batteries I can get upwards of 2 minutes from the same 24g drone.

BT2.0

I also have 1S 300mAh BT2.0 LiHV PILLOW batteries from the same unnamed brand as above.  They perform fairly well.

Yes, we all know that 1S batteries sag really bad when armed and flown, but then recover well when disarmed.  Fact of life with 1S.

However, the combination of 1S PILLOW and PH2.0 is one to avoid.

People have been recommending BT2.0 over PH2.0 for some time already.  However, if you have to use PH2.0, be sure to get only FOLDED batteries.

Overall summary:

FOLDED BT2.0 is the best.  3:30 flight time.

PILLOW BT2.0 is ok.  2:30 flight time.

FOLDED PH2.0 is ok.  2:00 flight time.

PILLOW PH2.0 is bad.  15 sec flight time.

The average current draw does determinate how well ph2 does fit, it needs to stay low. Sub25g with battery dowa work very well.

Sorry, but too many unstated variables.  You are indicating performance on year old 1S?   What prior use, frequency, current draw, stop voltage, charge voltage? How stored?  Solid or Rolled pin PH2?

A year is beyond a normal use lifetime for them, especially since unstated storage/use/etc over that time.

I have done a my own comparisons, taken two PH2 fitted quads, tested, then replaced connectors to A30/BT2 and tested again.

Readings measured with new cable connected cells, changing cell connectors between new PH2 (solid pin) and new A30/BT2. (Still a variable on quality of each, but as near as possible the same)

A30/BT2 gives around 30-45 seconds more flight, and less sag towards end of flight.

Folded against "pillow" is around the same time difference 25-40 seconds.

As you say, enough people have been down this road.  I really do not see PH2 as remotely adequate for modern higher current draw installations, particularly if using a current hungry HD VTX.

However, I still use PH2 on 150-200mAh cell low current drain uses for my club, but then, they are the ONLY type fitted on the sole battery source, and I'd have to change over 150.

I'm not THAT lunatic.............  

Solid pin PH2.0 and always stored at 3.85 volts for LiHV. They might have been just bad batteries, but the same brand, same age, same storage with BT2.0 work very well, all with the almost-same 1S birds at 24g, same aio, same motors, same props.