westfw, no change on the parens. I really believe it's a compiler issue. It works fine, 100% of the time, with just the call, but place something else around it, and it stops working. When I got down to just doing a "delay(1);" and it broke, I pretty much gave up.
I developed my own routines for handling these items when I ported an old program that expected 21,000 bytes of RAM to work on the Arduino's 2K (just an impractical amount of array storage to be useful), but I really thought I could simplify things once I found that all the Print:: functions were already handling __FlashStringStorage* (so why do it twice).
If I find anything new, I will share it here.