Hmm I don't do scry & die campaigns. So I don't know about that. Perhaps I am right on the other 2 points, but about the duration: why give more uses each per 2 class levels if it works continuously?
The problem is how poorly-worded the whole thing is. The intent is an alternate Scry mechanic. You're supposed to do it, watch for a bit, then come back to your body. That's why there's additional uses per day. However, Scry spells out that you can only keep watching for 1 min/level, and doesn't have that annoying flavour text about
actually going there, which causes all sorts of problems. Since you're suppose to go, see, and come back, it obviously lasts some period of time (an "instantaneous" peek would be rather odd). Since it doesn't say when it ends, apparently it doesn't unless you choose it to. You have mobility issues in that state, so a strict reading might make it so you can go and see as long as you like but can't move around without going back to your body and using it again... but a method of moving as a mental action could get around this.
The other thing is that it's a fundamentally more dangerous version, because distance is much more powerful than familiarity, especially with skillcheck DCs that scale so slowly. A Scryer must choose a creature, who gets a Will save, potentially with a pretty hefty Will save bonus. You also need some sort of connection to the creature, which is a substantial limit on the spell as well. You also can't scry anywhere that doesn't currently have people.
Sense Void on the other hand lets you go anywhere, regardless of a connection, will save, or abjurations. That's
huge. You can go places you've never been, never even
heard of, and now you know them for the purposes of scrying or teleporting. You can tell what's behind a locked door or in an enemy war-room far more reliably than by scrying.
I've used Scry-and-Die once and only once. It was late and we wanted to finish the campaign before dawn. In every other situation I have a lot of trouble seeing a DM letting Scry-and-Die go off, regardless of RAW, at least for the campaign boss. Now I haven't played with every DM ever, so my evidence is anecdotal only but a tactic that gets banned (or books thrown at you) isn't a good tactic.
The only campaign I've been in where one was used, the PCs had to raid this Dwarven fortress. There was only one enterance with ridiculous defenses, and the PCs had a hard time of it for a while. Then the Void Disciple SenseVoid'd into the centre of the facility, used his newfound familiarity to teleport them all right into the command room, and what was supposed to be a marathon session was over with trivial ease. Part of that was the DM's fault (he didn't expect them to have any way to teleport in), but it goes to show that, yes, it really does happen in actual games.
Anyway, this whole thing is predicated on my own rather fuzzy understanding of what the ability does. If someone can give a clearer RAW picture of how it's
not actually broken, that doesn't involve houserules (logical though they may be), I'd love it.