First, I'll just remind you and readers than, all too often, the "Field reports" we have read in various magazines tend to point of the features and say all sorts of nice things about the particular detector. I'm not saying all field reports are useless, just that you have to use a little caution with some of them.
That said, let me add this reminder regarding the excellent White's XL Pro, and it applies to each and every make and model of Target ID detector on the market. There is not such thing as a "perfect detectors" and there nothing to the myth that one brand's visual TID is "always accurate" or "can be trusted 100%"[/i] because, well they just aren't that good!
I read ahead and you also asked about the typical Target ID that you get from an Indian Head penny. The short answer is this: Most Indian Head cents, as well and many early 'wheatback' cents from 1909 to the early-to-mid 1920's, will usually produce a visual Target ID readout very similar to the modern US zinc cent."
The early "fat boy" Indian Heads and Flying Eagle cents read differently, and we must remember that ANY COIN, RING, OR OTHER METAL TARGET CAN READ 'OFF' from what we would expect under ideal (air or bench test) conditions depending upon the target's position, shape, wear, damage, and depth, as well as factors such as ground mineralization, ground moisture content, nearby masking targets, detector make and model, coil type and size, coil/target presentation, and operator related factors.
How can you know what target readings might be like at any given site? You dig the targets up.
I always suggest that when hunting a new site that you don't know anything about, set the detector up at the highest gain/sensitivity level you can handle w/o chatter, and use the lowest discriminate setting you can tolerate.
Then, for the next 30-45 minutes, or perhaps an hour if it takes that long to hit on a good enough number of targets to learn, you recover all iffy and good sounding target hits. ALL OF THEM.
You listen to how the target sounds, and you look to see what the TID reading is you get on a well-centered target sweep, and then you dig it up and take a look. In that 30-60 minute period you ought to have a good idea if there are many challenges at your site that can alter the Target ID, or if you're fortunate to be hunting in some decent ground and will have good to above average TID results.
Happy Hunting,
Monte