I really can't answer if you should update or not. Without remembering the specific model numbers, I have read some posts here(elsewhere?) that their owners have downgraded to certain revisions of firmware. For whatever preference or reason. Yet seeing those posts didn't pertain to the 855's that I own that info "went in one ear and out the other'.
And because of the above you really should direct your question to other 255w owners.
Sorry I can't be of more help ...........
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