Ariston GL4 lasted 12 years or so - Bosch replacement few months?

[appleimac]

I installed a Ariston 4 gallon electric water heater to supplement my weak hot water in my condo, plumbing it so the hot water entered the cold side, and would be be boosted to the correct temperature if necessary.  It had a cool on/off switch so I would just turn it off when leaving, turn it on before i needed it.  The only caveat is that I had to drain the tank every six months and change the anode rod, or it would be toast before long.  Many years later I think it developed a small leak, and I replaced it, I tried to buy the original Ariston but what came instead was the ugly Bosch replacement. This one has a ugly grey appearance, a dim indicator light, and to turn it off you must turn the temp dial all the way to off, and re-select the temp each time. Each of the two thermostat designs would have pros and cons, but I prefer the Ariston. The Bosch claims a "titanium lined tank" but I see no benefit to that - it doesn't stay clean any longer than the Ariston did. What really got me though is I was smelling a burning smell when the heater was on - I had turned up the temp more when using the dishwasher as I was getting a white film on brown melmac dishes, and was checking the temp where the hot water exited to see if anything was melting, and it wasn't.  Finally I pulled the faceplace off after unplugging, and found the left hand wire to the heating element totally blackened and burnt - why would this happen?  I didn't buy this at HD, but asked there today - and was told that the Bosch is cheaper design, and that I am not supposed to turn the heater off when leaving, just turn it way down - the instructions did not say I could not turn this unit off when I was gone - thoughts?