As an avid 3 gunner I like the idea. Only thing i don't like is restricting the l8ng range targets to 200yds and this is from someone who shoots Limited in 3 gun. For 200yds the most you'll likely need is a 3x magnifier which won't give much if any differences in rifle configurations between the divisions. 1-6+ won't be necessary, a 1-4x or 3x magnifier will be more than enough for all divisions, especially if a magnifier is allowed in the Practical division.
Also, no 10rd mag divisions, nobody wants that. I saw make the Practical division either 140mm mags or grip length mags with no magwell or extension.