I also prefer grep BLOCK LIST for the same reasons you give. Very occasionally, though, Perl mis-parses the left curly as introducing a hash reference constructor, and the error messages for this are far less than informative.

If this happens you can force Perl to parse the left curly as a block by immediately following it by a semicolon. That is, {; ... }.

The opposite mis-parse can also happen (Perl tries to parse a block when you wanted a hash reference). The fix for this is a unary plus before the left curly: +{ ... }.