I think that would be nice.

In fact, I was thinking of just adding a newramdisk: target
to the mkfile, w/ something like...
	cat <{echo -n xxxx} oldramdisk >newramdisk

On the other hand, wouldn't it be better to encourage people
to use the new boot loader (since otherwise they might break
their real power on switch)? 

Probably you know better than me which option is likely to
be more adequate.

BTW, I am very grateful to the one(s) who decided that sac.fs would be
a tar file. In general, I'm grateful to you all for keeping Plan 9  so
clean. It is orders of magnitude easier to modify/adapt it than it is
for the other systems I've seen.