Rob,
Even bi-wired the switch is still in the signal path to the woofers. I can say this from working on two different set's of RM-40's. The easiest (and easiest to reverse) way to remove the switch from the signal path is to solder a jumper from the center switch terminals - leading to the woofer XO, to the switch terminals leading to the woofer binding posts. On the two pairs I did this to these were the lower terminals. I used some 12ga Monster cable, in this case it was the old wire I removed from the mid/tweeter binding posts to the switch as both owners had no desire to make this reversible. Two short pieces, about 1 inch long is all that is needed, so most any quality wire should be OK and it can be bare, so insulation is not important.
You will still have the solder joints in the path but they are almost certainly less resistance than the switch contacts. FWIW one of the speakers I did this to had a failed switch so it was a more in the repair category than the mod category.
I don't know how much audible benefit there was to this but it could increase the bass damping a bit since it will lower the series resistance slightly (or not so slightly depending on the condition of the switch).
I imagine this will void your warranty but perhaps not. Brian would of course be the one to ask.
Mike