My advice is the same as jring/Joachim's, and like him, I expect that unless you have a lemon, you aren't likely to gain anything in resolution (that you asked about, specifically) by getting a new scope, especially if by that you mean more detail in your Iphone stills and movies. Scoping at distance tends to be limited more by atmospheric stability than by optics, and photography with a cell phone (no matter how good) or a small digital camera tends to be held back by the abilities of the sensor, especially if used at anything above base ISO. I think the biggest gains to be had with better scopes are control of chromatic aberration, ability to deal with back-lighting, and with getting good field of view and close focus specs.
My most often used scope is an ancient (~1996) but excellent Nikon 78ED Fieldscope with 30x MC eyepiece. I also sometimes use the 25-75x MC II zoom (often set to 75x) on that scope with a Sony RX100 iv camera to document rare river-dwelling turtles (seen as they are basking). I also have an excellent Nikon 82ED with 30x eyepieces, which should theoretically be better (brightness, contrast...), but the difference in performance is so small as to be inconsequential if even detectable in every circumstance in which I have tested it against the 78ED. I generally choose to use the 78ED simply because I prefer its focus collar placement (in front instead of behind the scope foot). I own 24x MC, 50x WF, 50x DS, 75x MC, and 25-56x MC eyepieces for these scopes, but they don't see much use.
I also have an Athlon 20-60x86ED Cronus scope, which I think it is similar to your Vortex, for my students to use. I haven't tested it in many real-world conditions because I don't use it much myself, but it seems a fine unit and a competent scope. I don't think that it lacks in resolution or visual quality at 60x, but I'm not that keen on it because I'm not a fan of traditional zoom eyepieces (with their poor FOV at ~30x magnification) and because it has poor (by my standards) close focus.
My latest addition is a Kowa TSN-884 with 25-60x. It's among the best in its class, and the zoom is certainly super nice with its excellent FOV at 25x (so wide that it gives up very little to fixed eyepieces), essentially constant AFOV, and very good eye-relief compared to the Nikon zoom. It's a great scope that provides a really clean view, and I will be acquiring the 1.6x extender in the near future for some photographic applications, which will make for a really nice package overall that will be useful for my research needs. Still, for routine birding, esp. since I'm not convinced of the need for powers over 30x for making IDs, I can't say that I find it a significant improvement over my 78ED. Perhaps I'll change my tune after a few years of comparative use, but that remains to be seen. Admittedly, despite being obsessive about my optics (eyeglasses, loupes, camera lenses, binos...), I've never been very inspired by scopes. Get a good one (such as you probably already have) and call it quits on purchasing more. I feel very differently about binoculars. I have, several times since ~1986, found new bins superior (optically or ergonomically) to my older ones and have then abandoned most use of the older ones almost immediately.
--AP