Yes RAT, we do lose out on other bookings. Like LOTM I often call them "Home visits" too.
I do like to get out and about, plus as they say it's less footfall at your door. I do also have the odd client who doesn't want to visit anywhere that might be 'known' WG premises, or who think they might risk bumping into other clients. So it can benefit WG as well as client.
For me it's not quite £50 extra, but I will only travel for around 45 minutes before expecting a longer booking(I find time rather than petrol costs are fairer in my part of the country). If someone is quite close I will usually come to some arrangement based upon my incall rate plus taxi fare if required. There are also far flung places, across my county that I will not visit without a hefty financial reward, this sometimes upsets some guys but not something I can help with.
So it has benefits for both punter as well as WG, but isn't for everyone. One big risk a WG takes is that they are sent to an address on a wild-goose chase.
Another problem I've come across has been guys claiming it will only take a certain time to get to a particular place, when I know it's a heck of a lot longer. Hefty discussions have ensued, but in such cases it usually turns out the client doesn't really want to see me anyway.
One little whinge I do have is that a lot of guys forget a visiting female may require soap, clean towels, loo roll and a warm house. I am pretty set in other ways myself so I can understand, but not excuse it!