To be sent after Turtle is in Last Call
The SPARQL and RDF working groups have been working to align SPARQL and Turtle syntax. The area of prefixed names is the main area of alignment.
The SPARQL Working Group has decided not to take the approach you propose of adopting a different syntax for prefixed names specifically for property paths. The syntax of prefix names in SPARQL and in Turtle (at last call) is the same.
The set of characters requiring escapes is the RFC 3986 'gen-delims' and 'sub-delims' except that there has been a change to allow the ":" character to be included unescaped into a prefix name in line with Turtle because the Open Graph Protocol uses this style and also it is the approach taken in URN schemes.
We hope that this reply responds your comment and would be grateful if you would acknowledge the response by sending a reply to this mailing list.
Andy, on behalf of the SPARQL-WG