Be honest now, how many times have you had to send back an ignition system or had it fail on you? I've flown with a lot of pilots, and many of them use engines on C&H Ignition or Syncrospark.
Now I'm not into the IMAC aircraft and trying to hover my airplane like a heli. I build and fly mostly warbirds. Some are scaled out more than others, but for the most part, they are pretty nice birds. I've run G-62's, Quadra 50's and 75's, and Lee 4.2 Sachs all on magneto. I can honestly say that I have never had a dead stick landing because of the fault of an engine. Now I've seen IMAC pilots and some warbird pilots have their ignition systems go out of timing, battery go bad, switch short out, all things that don't exist on a magneto sparked engine. I've seen Stinger Wallace swear that he'll never put another ignition system sparked engine in another airplane, and watched him fly the wings off of his Grumman Skyrocket with 2 G-62s. I'm running a Lee 4.2 Sachs on a 38 lb. 87" Hawker Sea Fury that's been clocked at 132 mph. That's enough power and fast enough for me. I've heard engines sputter and cough while the pilot prays for enough power to turn his plane around and land. I've been flying these large scaled gas burners for about 10 years now and if you don't mind, I'll keep it simple and stay with the magneto. I guarantee you that there isn't 200 rpms difference between a Sachs on ignition and a Sachs on Magneto. Your idle may be a little smoother (when it's running) but that's not enough to make me change my mind.
I know everyone has an opinion, and the above is just one man's ideas. I'm not trying to sell you on it. I don't care if you never run another engine on magneto. It's just my opinion and until somebody with one of those super 3W?!xz^-Z goes by me and blows my doors off, I'll just stick to what works for me, and most of the other guys that fly warbirds at our club).
Happy New Year to all and may all your landings be soft ones. !