While it's certainly possible that this is a usable version of Omega, be aware that when the upgrade to Omega 2 was released, it involved a procedure where the old LPT dongle was disabled during the upgrade procedure. There are lots of non working 1.5.6 dongles out there.
If it is working, it's a bargain at that price and will do an excellent job of running your Edge or it can serve as a trade in if you ever decide to upgrade to version 5 that will save you more than $150. You will need to have a computer with an LPT printer port to use it though. If you only have one LPT port and it's being used by your Edge, then you are well advised to add a second port for the dongle. Plugging the Edge into the dongle is a great way to blow the dongle out.