[c-nsp] loop guard still useful?

[Lee]

I just saw this bit about RSTP detecting unidirectional links:

http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst6500/ios/12-2SX/configuration/guide/book/spantree.html#wp1098785

  Detecting Unidirectional Link Failure

  Using the dispute mechanism included in the IEEE 802.1D-2004 RSTP
standard, the switch checks the consistency of the port role and state
in the received BPDUs to detect unidirectional link failures that
could cause bridging loops.

  When a designated port detects a conflict, it keeps its role, but
reverts to a discarding (blocking) state because disrupting
connectivity in case of inconsistency is preferable to opening a
bridging loop.


So I'm wondering if there's any reason to keep loop guard configured
on a switch?
Any current hardware that doesn't support rapidSTP?  Some other reason??

Thanks,
Lee