Per my semi-knowledge on this, it appears that Sleeper-6 has defined it rather well.
I can certainly attest to the notion of Hypereutectics "exploding" under detonation! I've blown a couple apart in an old motor, in more than one occasion. It is my understanding that because of the material difference, they react differently to heat, and therefore their rings have to be gapped differently than a regular cast or a forged. I know they were the "hot tip" for TR's years ago, and many people still run them today with great success. Keith Black wouldn't slap his name on them if they were crap...!
However, unless you build a completely non-detonating setup, then be prepared to replace them often. I know they can be made to work on the TR's, but my opinion is to simply spend roughly the same amount of money, and buy the TRW/Speed-Pro forged, or better yet, upgrade to a nice JE piston if the budget allows.
The last motor I built, I ran the TRW/SP forged versions for many years, without any piston failure. Yes, they're heavier, but they seem to be durable. I'm using them in my new motor too. Speed Pro Part # L2481F-30 Forged Pistons (-30 means bored 30 over)
All this aside, the fact still remains - detonation kills parts,,, period! Even a good forged piston will eventually give out under detonation. I guess my point is,,, "don't detonate!!!"