My opinions on this matter are no secret.
1. The 27 is superior. In every way. Period. More options, better finish, more features. Is the 28 bad? Of course not. It's just fine for what it is, a service grade revolver. Anyone who prefers the 28 for any reason is free to do so.
Yesterday I took a look at the exploded views and parts
diagrams in my Kuhnhausen shop manual for S&W revolvers.
Looking at the views of the 25, 27, 28 and 29, all internal
parts of the actions have the same part numbers except for
the TH & TTs. The standard trigger and hammers of the 27
have the same part numbers of the ones in the 28. If the
27 and 28 and 25 and 29 as well differ internally it must
be in some other way besides the parts because they are the
same.