I have both a Mk1 BV5 and a Mk1 7-32 and must say that I find the picture quality of the BV5 much better, especially the colours. Yes, it has less pixels and is not hd-ready but I still find it better. Have no experience of the Mk1 BV 7-40 but from what I have read at this forum the pq cannot be reagrded as good before you step up to the MK3:s, which are in a completely different price position.
Draw-backs of the BV5 would of course be that is has no inbuilt dvd as the BV7 and further no pc connection (if you for instance would like to connect a Beomaster 5 or a Mac Mini). Especially the lack of inbuilt dvd can be a problem since it is not always very easy to have them arranged in a good way if you do not want the dvd on floor behind or in side of the BV5 (I have never found the optional floor cabinet of the BV5 very attractive). I have solved this by hiding the dvd and the STB in a closet hanging on the other side of the wall and drilled a hole through the wall for all cables.