Warren,
I agree on your points...but I would like to mention a couple of the positives to converting if I may:

1/3 the size of fuel tank needed (which well offsets weight of ignition and battery), cheaper fuel, and lower constuption rate of fuel.

Another negitive is higher inital cost of motor, pumped carb, and time involved in conversion (unless you REALLY enjoy it).

I personally think ANY displacement above a 1.20 cu in is worth "playing with" if your up for the challenge.

Just don't expect a performance INCREASE by converting to gas in the smaller displacements.

Good Luck!
CrazyHerb