Dropping the \U+xxxx. syntax for unicode characters in strings

After having implemented the "\(...)" syntax for string embedding
(where that whole substring gets replaced by the character represented
by "#\..."), I'd like to recommend the "\U+xxxx." syntax for Unicode
characters be dropped in favour of the above mentioned syntax --
i.e. "\U+10A." would instead be written as "\(U+10A)".  

Rationale: reuse of character lexing code, less complicated logic
(only one syntax for multi-character escapes), and less error prone
syntax (I wouldn't have noticed the . in the \U+xxxx. syntax if
someone had not pointed it out on srfi-50).

Thougts?

-jivera