Foam sub roadbed advise needed

I need some advise Gang, A plan change required ripping up track work over a spline sub roadbed. The bench work is built lower where below the track scenery is needed except for a shallow dry creek bed and some ditches. Since I'm redoing it anyway I decided to just use foam over plywood for the whole thing. I noticed some blue foam that looks like its about 1/2" thick at Lowe's. This would be fine for me as far as thickness goes but I've only heard talk about using 1" and

2" material. My benchwork is rock solid. The plywood top is 1/2" supported about every foot except for a few spots where its a bit wider due to turnout locations and the turntable. You can run and jump on it and it won't give one iota but I've never used foam on a layout before. The actual roadbed will be WS foam and cork since I have plenty of it. Is there any reason not to use the 1/2" blue foam due to sound problems or anything else? Thanks, Bruce