Hi There
Yes, I have deployed a WLAN infrastructure that used in some parts the channels 1, 5, 9 and 13 in the way that you have described. The main reason we did it was that we had a need to put a lot of APs in a smal geographical area (because of building materials being non-conducive to radio penetration). We found that the .11b side of it worked pretty well all through, although occasionally a signal would be lost or slow response. But I have a feeling that is more the technology and outside factors more than the use of "slightly" overlapping channels.
Hope this helps.