How bad are these!?
Those switches are ****, generally speaking and in IME. All but one that I've had have needed replacement when under 5 years old. These were all in MIJ Fenders of the '90's. The one that has lasted is in my '94 Godin.
OTOH, the only open blade switch I've ever killed was one that I learned to solder on as a teenager, and that was in and out of guitars at least half a dozen times in its life. It became more and more beat up the more I resoldered it. Eventually (as in almost 20 years later), one of the solder tabs finally broke off. Even then, I could have jury-rigged it. But the switch was old, stiff, and looked like hell, so I just retired it. Long story short: Open blade switches are pretty durable and idiot-proof.
It's possible that the box switch you have won't break, at least not immediately. But it more likely than not will break some day down the line. When depends on how often, and how hard, you use it.
But even if it happens to be a well made switch, I find sealed switches annoying to work on, as I can't simply look at it to see what tabs do what. That's important to me, as I am not really knowledgeable in electronics. Without knowing the tabs by heart, I can at least look at a blade switch and see how it works, therefore how it needs to be wired. I can't do that with a boxed switch.
They also don't tolerate sloppy work and repeated solderings as well as the open blade switches. They are far more flimsy.
Bottom line: if a guitar came with a sealed switch like that, I would replace it the first time I happened to have the guitar opened up. I wouldn't open the guitar up just to replace one, though. In your case, you have it all opened up, so I would recommend replacing it.
