RE: DLE spark plugs!!!
The DLE plugs are real short on consistency. As previously noted somethimes you'll get one that works for awhile but frequently they will work only intermittantly, leaving the user quite perplexed sonsidering what is wrong with their engine.
The NKG plug will last well in excess of 100 hours of run time. If you tune your engines reasonably well the NGK should last you 4 years or more for the average weekend flyer. This is the reason buying a well made plug for a little more money is actually cheaper in the long run, plus your flying days are spent flying instead of troubleshooting.