Has anyone used the iOptron Skytracker Pro? If so, what did you think of it? easy to use? I am looking to pick one up shortly, but like to hear of others opinions of using it before buying one. I already have a sturdy tripod to use which should be plenty capable enough to hold the camera + lens + Skytracker, so am good there. Just wondering how well the iOptron works and if there are any similarly priced alternatives. Thanks.