display measure tool results in configurable projection

hi there, 

It would be nice if measure tool could display results in a user-defined projection. For example,original data source in  NAD 1983 UTM 17N, and this projection best fits for our regional area. In order to align with ArcGIS Online basemaps, when we publish a mp service, we set data frame level to be 102100 projection. it would be ideal if user can configure output projection, in our case, to be NAD 1983 UTM 17N (26917).  We tried to configure Projection WKID for "Planar" calculation Type under "Measurement" section for html5 viewer once, the result was not accurate to us. Thanks a lot !