I don't turn my engine off unless I have a landing option. The reason is that I might flood the engine when I try to restart (10-20% chance, I recon). From cold, I start with choke but no throttle. As soon as the engine coughs, I go 1/4 throttle and no choke. It usually starts then. If no start, I repeat with choke and no throttle. This usually works, but I end up flooding the engine 10-20% of the time. (I am open to suggestions on how to improve my mid-air technique.)
Also, when idling for an extended period, the plug can foul. I suggest you test your engine and see how long you can fly with the engine idling until it stops. I don't like to idle it for more than about 10 minutes. After that, I give the engine a little bit of a run to clean the plug, before idling again.
Pull vs. electric start. I find electric to be fine, but with some cautions regarding battery and maintenance. Firstly, get rid of the stock Ni-Cad battery. It is heavy, weak and takes overnight to charge. I use a Lithium-
Ferrous-Phosphate (not a Li-Po) battery. Its cranking power and stamina is far superior to the Ni-Cad, it weighs half as much, and it charges in less than 40 minutes. (The catch is that you need a voltmeter to care for the battery properly. Never let the resting voltage drop below 12.8 V, and never charge to above 14.6 V) I use an Ultrabatt single cell. Ref:
www.ultrabatt.com .
Secondly, periodically service your starter motor. Eventually the carbon brushes will need replacing, plus carbon dust from the brushes can build up inside the housing. If left un-serviced, your starter motor could die after a couple of busy seasons. (I will have mine serviced at the end of this season.)