EcoSmart 27 OnDemand Electric DHW panel heating element replacement - Copper or Titanium?

Hello
EcoSmart 27 Manual for reference
https://www.h2otek.com/tienda/pdf/a...SOELECTRICOLC3DNEAECOSMARTMOD_ECO18_24_27.pdf[

Issue with approximately 10 year old DHW panel:
The # 1 On Demand Electric Water Heating element ruptured and after the initial short along with a very possible loose screw connection that burned the one black load wire, the element measured Open Loop. Before replacing it I ran the cleaner thru it using a quart of Glug with 1 gallon of water for about 45 mins to clean all 3 elements of any buildup and it makes it a bit easier to remove them. I also opened a hot water faucet to assure the electronic flow module correctly turned power on to the Triacs. The temperature LEDs lit up and showed the temperature correctly. Then I checked the voltage at the 1st heating element and it read about 225 VAC. It did not read voltage at the second element so I suspect the first element which is the master was bad. The way the system works is that the 1st element is the workhorse and always turns on full and when the flow increases the flow module triggers the gate of the 2nd and 3rd triacs to power the 2nd and 3rd elements to keep the water hot. Then after turning the faucet off and turning the 3 breakers off, I checked the 3 limit snap discs on each element tube and they all had continuity. Then I checked the resistance from the gate to M1 input on all triacs which measured 30 ohms and the resistance between MT1 input and MT2 output which was open so they all shut off properly and none were shorted. To confirm the bad element the resistance between L1 and L2 of elements 2 and 3 were 6.3 ohms well within the 5 - 10 ohm spec. The resistance of element 1 was OL - Open Loop which is bad! So with a little twisting and turning, Pulling out element 1 was not hard using a Phillip screw driver and a 1-1/2” 6 point socket for 1/2” drive. Sure enough the it was ruptured!
The original elements are Copper and they do sell Titanium elements. Copper transfers the heat better and Titanium lasts longer and are more expensive. The panel has metal screw down connections on the terminal block so for the one wire that burned I used an 8 guage copper splice kit that will take the heat better!
I got the set of 3 generic brand copper heating elements for $50 so I now have 2 spares!
After installing the new element and connecting the wires to it, turning on the hot water faucet, it came on nice and hot.
BTW: The OEM copper elements have a black anti corrosion coating and the replacement ones do not.
I asked Google if the black coating on the OEM heating element inhibits the heat transfer and the answer was NO. See answer in the pic below.
See pics
Pic 1 - EcoSmart 27 with flush valves for cleaning
Pic 2 - Glug - used to flush heating elements.
Pic 3 - EcoSmart 27 electronics inside.
Pic 4 - EcoSmart 27 Element 1 - Ruptured
Pic 5 - EcoSmart 27 Element 1 - Ruptured Section
Pic 6 - EcoSmart 27 Element 1 - Ruptured Cleaned
Pic 7 - EcoSmart 27 Element 1 - Ruptured Section Cleaned
Pic 8 - OEM element black coating explained.