When it happened I was climbing a hill, noticed a power loss but it was still running. Then tried the hill again, power loss and then it died, I immediately noticed the lack of compression and did not try to start it back up.

The top of the piston shows where detonation has removed all traces of carbon and had death written all over the top of the piston before it burned the hole in the piston.

An engine that produced a piston that looks like the ones pictured was telling you that it was failing at least 5  seconds before the piston crown reached a high enough temperature for the top to blow through or to expand enough to start transferring alum to the cylinder or smearing over the rings with aluminum. 

You did notice something wrong but unfortunately you ignored it.  The sudden power loss is one of the many warning sign that something is wrong. The INSTANT you get one of these warning signs is when you grab the clutch and let off the throttle.  Most of the time a rider  that has had a lot of experience (blown up a lot of engines) riding two strokes would have heeded the warning sign "got of the throttle" and saved the piston from being damaged. 

I am not trying to make fun of you or belittle your riding experience but this is the only way riders gain experience and learn some of these signs of impending engine death, is by killing many pistons and other related engine components.  It took many pistons and crashes resulting from piston seizures when I raced motorcycles to get me to pay really close attention to every subtle change in engine tone, slight sag in power, vibration etc.  After enough engine failures you begin to remember those familiar sounds, or subtle power changes or vibrations that occurred just before some of your previous seized or holed pistons. 

High performance engines will not usually tolerate being very far out of tune without having failures if the rider does not heed the subtle warnings, stop and make the necessary changes to prevent the engine from failing.

If you had stopped the engine the instant you felt the power sag the 1st time, let it set for a minute and then slowly ridden it back to camp, removed the spark plug, you would have seen microscopic pepper like specks on the porcelain cone that surrounds the center electrode.  The microscopic pepper like specks on the spark plug are from the outer edges of the piston and head and will only appear on the spark plug when the engine is experiencing detonation.  Most of the time it requires a 2x to 5x magnifying glass to see these specks.

When you see these detonation specks on the spark plug the problem needs to be corrected before the engine is run hard again or you are going to kill another piston.

I do not believe in trying to build a recreational engine to run on pump premium.  If the engine requires 91 to 93 octane fuel to keep it from detonating and you actually get 93 octane from the gas station today, it will not be 93 octane in a day or two if the fuel was left in the fuel tank on the bike or in a plastic gas jug.  The fuel tank on the bike is vented and the plastic gas jugs are not usually absolutely air tight.  Fuel will keep for a year or more in a steel air tight can or drum.

The fuel tanks at the gas stations are vented and the octane rating also diminishes as time elapses.   Always buy fuel that has an octane rating that is at least a few points higher than what your race or recreational engine requires.  Our cars and trucks have computers that are making thousands of tuning adjustment every minute that will prevent the types of engine failures we see in our high performance recreational engines.  Our recreational and racing two stroke engines rely on the rider or his pit crew to make the necessary adjustments to keep the engine from failing.