Long flex hose would really reduce DC effectiveness... add a 30 foot run, I'd have to wonder if your dust collection would be much better than a shop vac.
I have 4 inch piping over a 20 foot run and 3 inlets to the system (650 CFM Wen) with waste gates. The closest one to the DC is the one for my planer, and about 6 feet of flex hose.... even when it was newly set up, it still struggled to keep up with the planer's output. However, if it is mostly just sanding dust and sweeping (and not a lot of heavy chips) you might be OK with what you're planning, just don't expect it to be as effective as it currently is. (My shop is about 18 x 24, for comparison.)
Since I have noticed that my furthest outlet at the lathe is also the least effective, I am thinking to pull out an inherited 6 gallon shop vac and plug that in at the lathe for sanding operations, and remove (or re-route) that 12 feet or so of 4 inch piping to other purposes... so the DC would mainly just handle the table saw, router table, and planer, and I'll run the big shop vac by the lathe for sanding, and the small (2 gallon) shop vac over on the 9 inch bandsaw & drill press benches.. and I suspect when I get around to doing that I'll probably see an improvement overall.