Ran my replacement bulbs for eight hours and then did some tests today.
Although the original Ecosmart ECS19WW120 and the replacement Definity DFN19WW120, look physically the same.
They are different.
When dimmed to a low level. You can see multiple small LEDs in the new bulb while the old one had two large arrays.
New one says 75mA and 8 watts on the bulb. I believe the older one used more power.
Kill-A-Watt Meter. Read 60mA, 6 watts and a PF of 0.95.
Worked OK with a 2456D3 Lamplinc, 2476D SwitchLinc Dimmer, three different hardware versions of an X10 LM465 Lamp Module,
Home Settings HA03 ZWave Lamp Module.
As expected Did not work with a X10 WS12A two wire dimmer.