Maybe Igor or Hans still remember that one of my first postings on the mailinglist was a question about the not so ideal visual appearance of the tags.
The problems are:
tags can shredder the layout as they may increase the leading (i. e. the distance between baselines of successive lines of text)
they cannot be simply agglomerated (in a segment with more than one tag and adding the tags at a certain position that is not the end, they will be agglomerated as 1222222 …
they do not necessarily help to distinguish spaces and full stops (see below, and look at it from a certain distance, and maybe it is easier to see with 4 and 5 than with other numbers)
they cannot be marked, so when marking source text with tags, you can never be sure if a leading or trailing tag is really marked or not
this is especially annoying when having a situation as below (and my reason for this posting). There are several occurrences of characters (maybe an arrow) not being recognized. You must not copy&paste the character alone once for all segments, as the different characters in different segments might be different. You must copy the whole sequence, hope that the tags have been copied and then tackle around to get it all right. Not the easiest way.