I haven't heard much on the Equinox. Pulsar is excellent at backing their product line with a 3 year warranty. I have looked through the 550's. It is a decent budget digital monocular. I might step it up a notch or if at all possible I would hold out for a thermal spotter like the Pulsar HD38 or the 19 if that is what the budget will live with.
definitely save a little longer for a thermal monocular. They're a game changer. I briefly owned the Pulsar HD19s. It's gonna be your best bang for your buck. Way better than the comparable flirs. Only reason I got rid of it is I got a killer deal on an eotech x320.