Are you sure your bypass valves are set correctly?  Every time someone mentions lukewarm water, or a burst of hot then back to cold, the valves aren't set right.

 

Recovery time is only a little longer on electric vs. propane and neither takes that long as Goose said.  If you use both modes you get a very fast recovery time, useful for multiple people that need a shower right after the other. 

 

The thermostat temps aren't much different between the modes, not enough that you can feel the difference - in other words, both are hot.  The electric mode is set a little lower to maintain the temperature so if you have both on you'll only use propane when you are actually using hot water.