There has been a lot of changes between 384.12 and 384.14 - and the biggest problem with our DSL routers is the limited nvram capacity.
So - after every successful firmware flash I run this command in SSH terminal ...
Code:
for line in `nvram show | grep =$ `; do var=${line%*=}; nvram unset $var; done; nvram commit
That frees up all the blank unused lines in nvram and reduces the used space a lot.
I always save my settings and backup the jffs folder - eject the USB - remove it from router - disable jffs scripts on the Administration tab ... restart the router without USB plugged in ... and only then do dirty flash to latest firmware. That ensures you have ample RAM for the flash process.
Reboot after dirty flash [still without USB plugged in] - wait 10 minutes - re-enable jffs scripts in the Admin tab - then pull the power cord on the router - wait for a minute - plug the USB into the router and power the router on.
So far I have been able to dirty flash all of Gnutons stable releases without a problem - so pretty sure you will be fine.
Do remember to run the above code
after you are happy that everything is configured correctly and working.