Thanks, folks!
That´s about what I feared. While I have desk time and run a round talking on the phone, working as a janitor is more often than not outside in rather loud surroundings, so the Vibe Alarm might be missed.
I´ll try to test-wear my W-735 to judge if the vibe alarm is of any use - If it is, I am eyeballing the GB 5600 just for teh silent alarm feature...