Can you install packages from STABLE in RELEASE?

[Henry Lenzi]

Hi --

 I'm currently running 6.0-SECURITY
 My portsnap tells me of a bunch of ports that have updates that, when
I head directly for an ftp site, I find on a STABLE tree (like
kde-3.5.3 - actually 3.5.2 until yesterday)

 For instance, ftp://ftp2.freebsd.org/pub/FreeBSD/ports/i386/packages-6.0-release/x11/
 lists kde-3.4.2.tbz

 Can I install these on RELEASE? If not, why does portsnap even suggest them?

 TIA.

 HL.