I have both.
The mag is a good deal if you need the weight and If you have a spring starter and that means more weight.
My EI engines all hand start easily and run better that the mag, but not by much.

With the mag if you don't spin it fast enough it doesn't generate spark so it won't start.
With out the spring started you need a HD starter and a good battery.
That's 125 to $150.00 plus you take it with you everytime.

When I fly my gas stuff I only take gas. I have enough battery to fly all day and if something goes wrong I fix it at home.
I've had more bad luck fixing something at the field and crashing later.
So Just take a backup.

K.I.S.S.