Lanefan
Victoria Rules
It's not quite as fast, to be sure, but ideally this would be part of an overall combat tweak where the slowdown here would be cancelled off by a streamlining elsewhere (in 5e this would start with a big reduction in hit points).Sounds too fiddly to me. While I get your problems with the standard initiative system; I think they're overridden by the benefits of its simplicity. There is no real bookkeeping or cognitive load to worry about; which lets you focus on making combat feel exciting. Your system sounds like its designed to make combat more fluid; but I think it would instead make it feel more jerky.
Also, I find when it comes to combat "more predictable" always equals "less exciting" and often "less interesting" as well.