I've been using the TSN-553 for several years for backpack hunting. Highly recommended where cutting weight is essential! It'll never replace my Swaro ATX, but for about half the weight, it definitely has its place for backpack hunts!
I hadn't seen the little Celestron Hummingbiurd scope (just looked it up). Intriguing, but at max 27x magnification, I'd almost rather just carry 18x binos. You get 45x on the Kowa and it's plenty usable. The Vortex Razor HD 11-33 is a good option if budget is a concern, but again, 33x top end vs 45x top end is a big difference.