My conclusion from these two occasions is that
the engine actually put out more power with ignition failure on one cylinder than
with compression failure.

Probably because if a valve sticks open, the intake manifold fuel
distribution to the other cylinders also becomes messed up.

If it is an exhaust valve that sticks open (and it probably was),
imagine what happens when the intake dutifuly opens at the same time
every 2 crankshaft revolutions. A big slug of exhaust gas gets sucked
up into the intake manifold, screwing up the mixture on the other
cylinders.

It is important to maintain the integrity of the intake manifold
system to maintain power output.