I've used this rate quite a few times in the past and never had a problem even when staying several nights at a hotel in London.
I have my contacts name and location printed on a piece of paper ready to give them when checking-in. As far as I recall I have only been asked once for it and even then they just looked and never noted it down.
I always guarantee my bookings with a current credit card. It may well be that those hotels who are asking for further info on F&F bookings have suffered in the past from people booking this rate and not showing up. Or from people making and cancelling multiple bookings. Then again, an easy fix for that problem would be to make it a pay up front rate.