Valid points. Yes, I've heard the TG15 CD is less reliable. I guess I want to see for myself, and maybe try to fix it or get it fixed somewhere. I guess I'm trying to be optimistic lol.
Personally fragility does not worry me at all. I know some units are more prone to breaking than others but every electronic breaks, especially old game hardware. Any used hardware over a decade old could have potentially seen a lot of abuse and be on its last legs since it has likely changed hands a few times.
But realistically anything you buy will give you a few years of good service if you plan to use it lightly, only playing a few games here and there then disconnecting the unit and putting it away until next time.
Even the notorious caps on the early PC Engine hardware cannot possibly have a fail rate of a hundred percent, it is always a gamble, the stakes are just higher.