Is Zefon now recommending that customers consider the CSI version for all their sampling?

No. It would not be economically feasible to use the CSI product on every sample. Users should understand their options, and informed what it will do. This is another tool at your disposal to diagnose IAQ problems. If you have already somehow determined there is a non biological problem, or you have already performed a standard Air-O-Cell analysis which demonstrates a non-biological problem, then is great time to consider using the CSI version to help both identify what it is, and trace down the source.