Bit unfair of me to add anything to this post as we have the flip-up rear seats and therefore have the luxury of a removable conversion
But I will anyway, because I know how often the conversion is a useful thing, and how often it's surplus to requirements.
If there's two of us (me and the boy), we use the conversion and usually no awning.
If there's three of us (me, hubby and boy), and it's a one or two nighter, we use the conversion and a utility tent.
If there's three of us and we're on holiday, the conversion stays at home, the seat goes back in and we use the Bongo as the bedroom and our driveway awning for cooking/living.
On weeks out of 52 that the conversion is in the Bongo, I'd say it's fewer than 26 as that gives us more seating or more boot space depending on what we're up to. We normally keep it in over the Autumn/Winter months, as it makes the Bongo into a nice retreat after a cold, wet walk. Much cheaper than a cafe and it makes you popular with your friends!!
It's also useful to have a sink for washing muddy hands after an acorn collecting expedition!!!!!!
As advised before, live without a conversion and find out what you are really using your Bongo for before you decide to take the plunge.