Why are you using Link2SD with Oxygen? Oxy includes an a2sd script, and if you want to move the dalvik there's a patch for that. OK, Link2SD does let you move individual apps to different places, but that's the only thing I can think of.
Mind you, it's odd that it only works with ext2 - I have played with it, and used it with ext4 myself.
1.5G would be quite big enough for the partition, so it's not likely to be that.
Bootloop after wiping dalvik, but not after factory reset, may well be Link2SD. If you have the stock 147MB internal space and a lot of apps, you may not have space for everything internally. When you wipe the dalvik cache it will be rebuilt, but if you moved it using Link2SD it will need moving again after a wipe. So if the dalvik is rebuilt in internal space when you boot, and there isn't enough room for all of your apps + data + dalvik cache, that could well cause a bootloop (depending on when it runs out of space). Won't happen after a factory reset as the user apps and their data are also gone.
But it doesn't explain why simply rebooting the phone (or powering off) would cause problems. That's the real puzzle.