What are the true differences, pro's and cons...between f-75 and F-70...?

I know the f-75 can be more sensitive, but the 70 is less bothered by electrical interference...any opinions here on this?

-mike

Andy NM seems to have all the answers on the forum and has used both units and perhaps he can give you some info.Only used an F70 and it seems to me most of the clics etc. can be attributed to small particles in the ground not outside interferences. Simply swing it in air if stable its the ground and some are confusing either...