/etc/fstab in NetBSD < current when device numbers are variable

["Thomas Mueller" <mueller6724%bellsouth.net@localhost>]

I have the problem with NetBSD finding its root when installed to USB stick, or 
other device where the root device number/name could vary.  This plays havoc 
with booting.

How do I overcome this problem in NetBSD 6.x and 5.x, or am I limited to HEAD 
and GPT, using "NAME="?  Though I don't really want to keep up with NetBSD 
releng-5 on my modern hardware.

If I go to boot prompt and enter
boot netbsd -a
boot is likely to hang at root-device prompt, requiring Reset button.

Maybe I need to stick with NetBSD-current and GPT?

Tom