Please give it a try in configurations that are important for you and
report any problems you have, either on this mailing list, or
(preferably) via our bug tracker at
https://bugs.kde.org/enter_bug.cgi?product=valgrind
The final 3.27.0 release is scheduled for Mon Apr 20.
See my other reply for contents. Changed since RC0:
Copyright notices, Linux fsconfig syscall fix, s390 instruction selection bug, macOS build failure from distribution tarballs, a few more opcodes handled on x86.