If you go for a SOOPD, be aware that there are three versions, which need to match your lens. The earliest uses a screw clamp, and is for Summitar lenses with no groove around the front. The other two latch onto a groove on around the lens, the earlier groove is a V-groove, and the later is a flat-bottomed U-groove.
The SOOPD is a good choice on a screwmount Leica. The "ventilation holes" are in the wrong place for an M-mount Leica, where the round hood would be better. The SOOPD provides the best protection from flare, by far.